Surface position detecting apparatus, exposure apparatus, surface position detecting method, and device manufacturing method

ABSTRACT

A surface position detecting apparatus according to an aspect of the present invention has a light-sending optical system which makes first light and second light from first and second patterns incident at different incidence angles to a predetermined surface to project an intermediate image of the first pattern and an intermediate image of the second pattern onto the predetermined surface; a light-receiving optical system which guides the first light and the second light reflected by the predetermined surface, to a first observation surface and to a second observation surface, respectively, to form an observation image of the first pattern and an observation image of the second pattern on the first and second observation surfaces; and a detecting section which detects a piece of position information of the observation image of the first pattern and a piece of position information of the observation image of the second pattern and calculates a surface position of the predetermined surface, based on the pieces of position information. The light-sending optical system has a sending-side reflecting section which reflects the second light having passed via sending-side common optical members, an even number of times to make the second light incident at the incidence angle smaller than that of the first light to the predetermined surface.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priorities fromU.S. Provisional Application No. 61/136,485, filed on Sep. 9, 2008, theentire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field

The present invention relates to a surface position detecting apparatus,exposure apparatus, surface position detecting method, and devicemanufacturing method to detect a surface position of a predeterminedsurface.

2. Description of the Related Art

In an exposure apparatus which transfers a pattern formed on a mask,through a projection optical system onto a photosensitive substrate, itis sometimes the case that the depth of focus of the projection opticalsystem is shallow and that a photosensitive surface (transfer surface)of the photosensitive substrate is uneven. For this reason, the exposureapparatus needs to perform accurate alignment of the photosensitivesurface of the photosensitive substrate with an image plane of theprojection optical system.

For example, an oblique incidence type autofocus sensor is known as asurface position detecting apparatus which detects a surface position ofthe photosensitive substrate (surface position of the photosensitivesurface) along the optical-axis direction of the projection opticalsystem (cf. Japanese Patent Application Laid-open No. 4-215015). Thisoblique incidence type autofocus sensor is configured to project animage of a slit from an oblique direction to the photosensitivesubstrate as a predetermined surface, detect position information of theimage of the slit formed by light reflected on the predeterminedsurface, and detect the surface position of the photosensitivesubstrate, based on the position information.

SUMMARY

The foregoing oblique incidence type autofocus sensor had the problemthat it was unable to accurately detect the surface position of thephotosensitive substrate if there occurred variation in an opticalmember (variation in position, variation in refractive index, etc.) inan optical system constituting the oblique incidence type autofocussensor.

Aspects of the present invention have been accomplished in view of theabove-described problem and aspects of the present invention provide asurface position detecting apparatus, an exposure apparatus, a surfaceposition detecting method, and a device manufacturing method capable ofhighly accurately detecting the surface position of the predeterminedsurface while suppressing influence of variation in an optical member.

For purposes of summarizing the invention, certain aspects, advantages,and novel features of the invention have been described herein. It is tobe understood that not necessarily all such advantages may be achievedin accordance with any particular embodiment of the invention. Thus, theinvention may be embodied or carried out in a manner that achieves oroptimizes one advantage or group of advantages as taught herein withoutnecessary achieving other advantages as may be taught or suggestedherein.

A surface position detecting apparatus according to a first aspect ofthe present invention is a surface position detecting apparatus fordetecting a surface position of a predetermined surface, the apparatuscomprising: a light-sending optical system which makes first light froma first pattern and second light from a second pattern incident atdifferent incidence angles to the predetermined surface to project anintermediate image of the first pattern and an intermediate image of thesecond pattern onto the predetermined surface; a light-receiving opticalsystem which guides the first light and the second light reflected bythe predetermined surface, to a first observation surface and to asecond observation surface, respectively, to form an observation imageof the first pattern on the first observation surface and an observationimage of the second pattern on the second observation surface; and adetecting section which detects a piece of position information of theobservation image of the first pattern on the first observation surfaceand a piece of position information of the observation image of thesecond pattern on the second observation surface and which calculates asurface position of the predetermined surface, based on the pieces ofposition information, wherein the light-sending optical system has atleast one sending-side common optical member provided in common to thefirst light and the second light, and a sending-side reflecting sectionwhich reflects the second light having passed via the sending-sidecommon optical member, an even number of times to make the second lightincident at the incidence angle smaller than that of the first light tothe predetermined surface.

Another surface position detecting apparatus according to a secondaspect of the present invention is a surface position detectingapparatus for detecting a surface position of a predetermined surface,the apparatus comprising: a first detecting system which makes firstlight from a first pattern incident to the predetermined surface toproject an intermediate image of the first pattern onto thepredetermined surface, which guides the first light reflected by thepredetermined surface, to a first observation surface to form anobservation image of the first pattern on the first observation surface,and which detects position information of the observation image of thefirst pattern on the first observation surface; a second detectingsystem which makes second light from a second pattern incident to thepredetermined surface to project an intermediate image of the secondpattern onto the predetermined surface, which guides the second lightreflected by the predetermined surface, to a second observation surfaceto form an observation image of the second pattern on the secondobservation surface, and which detects position information of theobservation image of the second pattern on the second observationsurface; and a processing section which calculates a surface position ofthe predetermined surface, based on the position information of theobservation image of the first pattern and the position information ofthe observation image of the second pattern, wherein the first detectingsystem and the second detecting system have at least one sending-sidecommon optical member provided in common to the first light and thesecond light, and wherein the second detecting system has a sending-sidereflecting section which reflects the second light having passed via thesending-side common optical member, an even number of times to make thesecond light incident at an incidence angle smaller than an incidenceangle of the first light, to the predetermined surface.

An exposure apparatus according to a third aspect of the presentinvention is an exposure apparatus for transferring a pattern to aphotosensitive substrate mounted on a substrate stage, the exposureapparatus comprising: the surface position detecting apparatus of thefirst or second aspect of the present invention, which detects a surfaceposition of a photosensitive surface of the photosensitive substrate;and an aligning mechanism which achieves alignment of the substratestage, based on a detection result of the surface position detectingapparatus.

Another exposure apparatus according to a fourth aspect of the presentinvention is an exposure apparatus for transferring a pattern of a maskmounted on a mask stage, to a photosensitive substrate mounted on asubstrate stage, the exposure apparatus comprising: the surface positiondetecting apparatus of the first or second aspect of the presentinvention, which detects a surface position of at least one of aphotosensitive surface of the photosensitive substrate and a patternsurface of the mask; and an aligning mechanism which achieves relativealignment between the substrate stage and the mask stage, based on adetection result of the surface position detecting apparatus.

A surface position detecting method according to a fifth aspect of thepresent invention is a surface position detecting method for detecting asurface position of a predetermined surface, the method comprising thesteps of: making first light from a first pattern and second light froma second pattern incident at different incidence angles to thepredetermined surface to project an intermediate image of the firstpattern and an intermediate image of the second pattern onto thepredetermined surface; guiding the first light and the second lightreflected by the predetermined surface, to a first observation surfaceand to a second observation surface, respectively, to form anobservation image of the first pattern on the first observation surfaceand an observation image of the second pattern on the second observationsurface; and detecting a piece of position information of theobservation image of the first pattern on the first observation surfaceand a piece of position information of the observation image of thesecond pattern on the second observation surface, and calculating asurface position of the predetermined surface, based on the pieces ofposition information, wherein the step to project an intermediate imageof the first pattern and an intermediate image of the second patterncomprises making the first light and the second light travel via atleast one sending-side common optical member provided in common to thefirst light and the second light, and reflecting the second light havingpassed via the sending-side common optical member, an even number oftimes to make the second light incident at the incidence angle smallerthan that of the first light to the predetermined surface.

Another surface position detecting method according to a sixth aspect ofthe present invention is a surface position detecting method fordetecting a surface position of a predetermined surface, the methodcomprising the steps of making first light from a first pattern incidentto the predetermined surface to project an intermediate image of thefirst pattern onto the predetermined surface, guiding the first lightreflected by the predetermined surface, to a first observation surfaceto form an observation image of the first pattern on the firstobservation surface, and detecting position information of theobservation image of the first pattern on the first observation surface;making second light from a second pattern incident to the predeterminedsurface to project an intermediate image of the second pattern onto thepredetermined surface, guiding the second light reflected by thepredetermined surface, to a second observation surface to form anobservation image of the second pattern on the second observationsurface, and detecting position information of the observation image ofthe second pattern on the second observation surface; and calculating asurface position of the predetermined surface, based on the positioninformation of the observation image of the first pattern and theposition information of the observation image of the second pattern,wherein the step of detecting position information of the observationimage of the first pattern and the step of detecting positioninformation of the observation image of the second pattern comprisemaking the first light and the second light, respectively, travel via atleast one sending-side common optical member provided in common to thefirst light and the second light, and wherein the step of detectingposition information of the observation image of the second patterncomprises reflecting the second light having passed via the sending-sidecommon optical member, an even number of times to make the second lightincident at an incidence angle smaller than an incidence angle of thefirst light, to the predetermined surface.

A device manufacturing method according to a seventh aspect of thepresent invention is a method comprising: transferring the pattern ontothe photosensitive substrate, using the exposure apparatus according tothe third or fourth aspect of the present invention; and processing thephotosensitive substrate to which the pattern has been transferred,based on the pattern.

BRIEF DESCRIPTION OF THE DRAWINGS

A general architecture that implements the various features of theinvention will now be described with reference to the drawings. Thedrawings and the associated descriptions are provided to illustrateembodiments of the invention and not to limit the scope of theinvention.

FIG. 1 is a drawing showing a configuration of an exposure apparatuswith a surface position detecting apparatus according to an embodimentof the present invention.

FIG. 2 is a drawing showing a configuration of a surface positiondetecting apparatus according to a first embodiment example of theembodiment.

FIG. 3 is a drawing showing a plurality of light-sending slits providedon an exit face of a light-sending prism for measurement light.

FIG. 4 is a drawing showing a plurality of light-sending slits providedon an exit face of a light-sending prism for reference light.

FIG. 5 is a drawing showing a configuration from a sending-side rhombicprism to a receiving-side rhombic prism.

FIG. 6 is a view along the Z-direction of an optical path of measurementlight and an optical path of reference light in FIG. 5.

FIG. 7 is a drawing schematically showing a state in which anintermediate image of a measurement pattern and an intermediate image ofa reference pattern are arrayed in the same row and at the same locationon a detection target surface.

FIG. 8 is a drawing showing a plurality of light-receiving slitsprovided on an entrance face of a light-receiving prism for measurementlight.

FIG. 9 is a drawing showing a plurality of light-receiving slitsprovided on an entrance face of a light-receiving prism for referencelight.

FIG. 10 is a drawing showing a plurality of light-receiving portionsprovided on a detection surface of a photodetector for measurementlight.

FIG. 11 is a drawing showing a plurality of light-receiving portionsprovided on a detection surface of a photodetector for reference light.

FIG. 12 is a drawing showing a configuration of a surface positiondetecting apparatus according to a second embodiment example.

FIG. 13 is a drawing showing a configuration from a sending-side rhombicprism to a receiving-side rhombic prism in FIG. 12.

FIG. 14 is a view along the Z-direction of an optical path ofmeasurement light and an optical path of reference light in FIG. 13.

FIG. 15 is a drawing schematically showing a state in which anintermediate image of a measurement pattern and an intermediate image ofa reference pattern are arrayed in parallel on a detection targetsurface in the second embodiment example.

FIG. 16 is a drawing showing a plurality of light-receiving portionsprovided on a detection surface of a photodetector in the secondembodiment example.

FIG. 17 is a drawing showing a configuration of a surface positiondetecting apparatus according to a third embodiment example.

FIG. 18 is a drawing showing a configuration from a sending-side rhombicprism to a receiving-side rhombic prism in FIG. 17.

FIG. 19 is a view along the Z-direction of an optical path ofmeasurement light and an optical path of reference light in FIG. 18.

FIG. 20 is a drawing to illustrate an action of reflecting prisms usedin the third embodiment example.

FIG. 21 is a drawing to illustrate a form of reflecting prisms used inthe third embodiment example.

FIG. 22 is a drawing showing a configuration example of a sending-sidereflecting section and a receiving-side reflecting section in anintegrated form.

FIG. 23 is a drawing showing a modification example of a sending-sidedeflecting section and a receiving-side deflecting section.

FIG. 24 is a drawing schematically showing an example in which elementpatterns in an intermediate image of a measurement pattern and elementpatterns in an intermediate image of a reference pattern are alternatelyarrayed along one direction.

FIG. 25 is a drawing schematically showing an example in which aplurality of element patterns in an intermediate image of a measurementpattern and a plurality of element patterns in an intermediate image ofa reference pattern are arrayed as superimposed in a matrix pattern.

FIG. 26 is a drawing schematically showing an example in which aplurality of element patterns in an intermediate image of a measurementpattern and a plurality of element patterns in an intermediate image ofa reference pattern are alternately arrayed in a matrix pattern.

FIG. 27 is a drawing showing a configuration example of light-sendingslits for measurement light and light-sending slits for reference lightprovided in a common pattern surface of a light-sending member.

FIG. 28 is a flowchart showing manufacturing steps of semiconductordevices.

FIG. 29 is a flowchart showing manufacturing steps of a liquid crystaldevice.

DESCRIPTION

An embodiment of the present invention will be described on the basis ofthe accompanying drawings. FIG. 1 is a drawing showing a configurationof an exposure apparatus with a surface position detecting apparatusaccording to the embodiment of the present invention. FIG. 2 is adrawing showing a configuration of the surface position detectingapparatus according to a first embodiment example of the embodiment. InFIG. 1, the Z-axis is set along a direction of the optical axis AX ofprojection optical system PL, the X-axis in parallel with the plane ofFIG. 1 in a plane perpendicular to the optical axis AX, and the Y-axisperpendicularly to the plane of FIG. 1 in the plane perpendicular to theoptical axis AX.

In each of embodiment examples of the present embodiment, the surfaceposition detecting apparatus of the present invention is applied todetection of a surface position of a photosensitive substrate to which apattern is to be transferred in the exposure apparatus.

The exposure apparatus shown in FIG. 1 is provided with an illuminationsystem IL to illuminate a reticle R as a mask on which a predeterminedpattern is formed, with illumination light (exposure light) emitted froma light source for exposure (not shown). The reticle R is held inparallel with the XY plane on a reticle stage RS. The reticle stage RSis two-dimensionally movable along the XY plane by action of a drivingsystem omitted from the illustration and is so configured thatcoordinates of its position are measured by a reticle interferometer(not shown) and that the position is controlled based thereon.

The exposure light transmitted by the reticle R travels through theprojection optical system PL to form an image of the pattern of thereticle R on a surface (photosensitive surface) Wa of a wafer W being aphotosensitive substrate. The wafer W is held in parallel with the XYplane on a Z-stage VS. The Z-stage VS is loaded on an XY stage HS whichmoves along the XY plane parallel to the image plane of the projectionoptical system PL. The Z-stage VS is operated by action of a drivingsystem VD in accordance with a command from a controller CR to adjust afocus position (position in the Z-direction) and an inclination angle(inclination of the surface of the wafer W relative to the XY plane) ofthe wafer W.

The Z-stage VS is provided with a moving mirror (not shown) and a waferinterferometer (not shown) using this moving mirror measures a positionin the X-direction, a position in the Y-direction, and a position in adirection of rotation around the Z-axis, of the Z-stage VS in real timeand outputs the measurement results to the controller CR. The XY stageHS is mounted on a base (not shown). The XY stage HS is operated byaction of a driving system HD in accordance with a command from thecontroller CR to adjust a position in the X-direction, a position in theY-direction, and a position in the direction of rotation around theZ-axis, of the wafer W.

For well transferring a circuit pattern on the pattern surface of thereticle R into each exposure region on the photosensitive surface Wa ofthe wafer W, it is necessary to align a current exposure region within arange of width of focal depth centered at the image plane by theprojection optical system PL, for every exposure into each exposureregion. It can be implemented by accurately detecting a position alongthe optical axis AX of each point in the current exposure region, i.e.,a surface position of the current exposure region and then carrying outleveling of the Z-stage VS (adjustment of the inclination angle of thewafer W; horizontal alignment) and movement in the Z-direction thereof,and thereby carrying out leveling of the wafer W and movement in theZ-direction thereof. For that, the exposure apparatus of the presentembodiment is equipped with the surface position detecting apparatus fordetecting the surface position of the exposure region.

As shown in FIG. 1, the surface position detecting apparatus of thefirst embodiment example has a light-sending unit 101 and alight-receiving unit 102. As shown in FIG. 2, the light-sending unit 101has a light source 1A for measurement light, a light source 1B forreference light, condenser lenses 2A, 2B, light-sending prisms 3A, 3B, adichroic mirror 4, a second objective lens 5, a vibrating mirror 6, afirst objective lens 7, a rhombic prism 8, and an angle-deviating prism10. The light-receiving unit 102 has relay lenses 22A, 22B,light-receiving prisms 23A, 23B, a dichroic mirror 24, a secondobjective lens 25, a mirror 26, a first objective lens 27, a rhombicprism 28, and an angle-deviating prism 30. In general, the surface ofthe wafer W being a detection target surface is coated with a thin filmof a resist or the like. Therefore, in order to reduce influence ofinterference due to this thin film, the light sources 1A and 1B arepreferably white light sources with a broad wavelength band (e.g.,halogen lamps to supply illumination light in a wavelength band of600-900 nm, xenon light sources to supply illumination light in a broadwavelength band equivalent thereto, and so on). Light emitting diodes tosupply light in a wavelength band with low photosensitivity to theresist can also be used as the light sources 1A and 1B.

The light from the light source 1A travels through the condenser lens 2Ato enter the light-sending prism 3A. The light-sending prism 3A deflectsthe light from the condenser lens 2A toward the subsequent dichroicmirror 4 (not shown in FIG. 1) by its refracting action. There are fivelight-sending slits Sm1, Sm2, Sm3, Sm4, and Sm5 for measurement lightarrayed, for example as shown in FIG. 3, on an exit face 3Aa of thelight-sending prism 3A.

In FIG. 3, a y1-axis is set along a direction parallel to the Y-axis ofthe global coordinate system on the exit face 3Aa and an x1-axis along adirection perpendicular to the y1-axis on the exit face 3Aa. Thelight-sending slits Sm1-Sm5 are, for example, optically transparentportions of a rectangular shape (slit shape) elongated in an obliquedirection at 45° to the x1-direction and the y1-direction, and theregion other than the light-sending slits Sm1-Sm5 is a light shieldportion. The light-sending slits Sm1-Sm5 as a measurement pattern arearrayed in a row and at a predetermined pitch along the x1-direction.

Similarly, the light from the light source 1B travels through thecondenser lens 2B to enter the light-sending prism 3B. The light-sendingprism 3B deflects the light from the condenser lens 2B toward thedichroic mirror 4 by its refracting action. There are five light-sendingslits Sr1, Sr2, Sr3, Sr4, and Sr5 for reference light arrayed, forexample as shown in FIG. 4, on an exit face 3Ba of the light-sendingprism 3B.

In FIG. 4, a y2-axis is set along a direction parallel to the Y-axis ofthe global coordinate system on the exit face 3Ba and an x2-axis along adirection perpendicular to the y2-axis on the exit face 3Ba. Thelight-sending slits Sr1-Sr5 are, for example, optically transparentportions of a rectangular shape (slit shape) elongated in an obliquedirection at 45° to the x2-direction and the y2-direction, and theregion other than the light-sending slits Sr1-Sr5 is a light shieldportion. The light-sending slits Sr1-Sr5 as a reference pattern arearrayed in a row and at a predetermined pitch along the x2-direction.

As described above, the light source 1A and condenser lens 2A constitutean illumination system for measurement light to illuminate thelight-sending slits Sm1-Sm5 and the light source 1B and condenser lens2B constitute an illumination system for reference light to illuminatethe light-sending slits Sr1-Sr5. The light-sending slits Sm1-Sm5 as themeasurement pattern are an array pattern in which five element patternsare arrayed in a row and at the predetermined pitch along thex1-direction.

The light-sending slits Sr1-Sr5 as the reference pattern are an arraypattern in which five element patterns are arrayed in a row and at thepredetermined pitch along the x2-direction. As described later, avariety of modification examples can be contemplated as to the shape,number, arrangement, etc. of the element patterns forming themeasurement pattern and the reference pattern.

The measurement light having passed through the light-sending slitsSm1-Sm5 is transmitted by the dichroic mirror 4 and thereafter travelsvia the second objective lens 5, the vibrating mirror (not shown in FIG.2) 6 as a scanning means, and the first objective lens 7 to enter therhombic prism 8. The reference light having passed through thelight-sending slits Sr1-Sr5 is reflected by the dichroic mirror 4 andthereafter travels via the second objective lens 5, vibrating mirror 6,and first objective lens 7 to enter the rhombic prism 8.

The second objective lens 5 and the first objective lens 7 cooperate toform intermediate images of the light-sending slits Sm1-Sm5 andintermediate images of the light-sending slits Sr1-Sr5. The vibratingmirror 6 is arranged at the front focus position of the first objectivelens 7 and is configured so as to be rockable around the Y-axis asindicated by arrows in FIG. 2. The rhombic prism 8 is a prism member ofa columnar shape having a cross section of a parallelogram along the XZplane and extending in the Y-direction. As shown in FIG. 2, a dichroicfilm 9 is formed on a lower side face in the drawing of the rhombicprism 8 and the angle-deviating prism 10 is attached in proximity tothis dichroic film 9. The cross-sectional shape of the rhombic prismdoes not have to be limited to a parallelogram, but may be an elongatedrhombic shape (rhomboid).

The measurement light Lm incident through an entrance face 8 a of therhombic prism 8 along a measurement optical path indicated by a solidline in FIG. 5 is reflected by a reflecting face 8 b and thereafter isincident to the dichroic film 9 formed on the side face 8 c. Themeasurement light Lm reflected by the dichroic film 9 is emitted from anexit face 8 d of the rhombic prism 8 and is then incident from anoblique direction along the XZ plane to a detection area DA on thephotosensitive surface Wa as a detection target surface. An incidenceangle θm of the measurement light Lm is set to a large angle, e.g.,between 80° inclusive and 90°.

On the other hand, the reference light Lr incident through the entranceface 8 a of the rhombic prism 8 along a reference optical path asindicated by a dashed line in FIG. 5 is reflected by the reflecting face8 b and passes through the dichroic film 9 to enter the angle-deviatingprism 10. As shown in FIG. 6, the optical path of the measurement lightLm incident to the rhombic prism 8 is coincident with the optical pathof the reference light Lr incident to the rhombic prism 8. The referencelight Lr incident into the angle-deviating prism 10 is reflected by areflecting face 10 a thereof, travels through the dichroic film 9, andis emitted obliquely upward in FIG. 5 from the exit face 8 d of therhombic prism 8.

Namely, the dichroic film 9 has a characteristic opposite to that of thedichroic mirror 4 as to the separating action of light depending uponwavelengths. The reference light Lr emitted from the exit face 8 d isincident into a reflecting prism 11, for example, of a prismatic shapeextending in the Y-direction. The reference light Lr incident into thereflecting prism 11 is successively reflected by its reflecting faces 11a and 11 b and then is incident from an oblique direction to thedetection area DA and along a plane of incidence (XZ plane) of themeasurement light Lm to the photosensitive surface Wa. An incidenceangle θr of the reference light Lr is set to an angle smaller than theincidence angle θm of the measurement light Lm. The incidence angle θrof the reference light Lr is preferably not more than 45° and morepreferably not more than 30°.

In this way, as schematically shown in FIG. 7, intermediate images Im1,Im2, Im3, Im4, and Im5 of the light-sending slits Sm1-Sm5 as themeasurement pattern are projected onto the detection area DA on thephotosensitive surface Wa. Namely, the five intermediate images Im1-Im5elongated in an oblique direction at 45° to the X-direction and theY-direction are formed at a predetermined pitch along the X-direction,corresponding to the light-sending slits Sm1-Sm5, in the detection areaDA. Centers of the respective intermediate images Im1-Im5 correspond topredetermined detection points in the detection area DA.

Similarly, intermediate images Ir1, Ir2, Ir3, Ir4, and Ir5 of thelight-sending slits Sr1-Sr5 as the reference pattern are projected ontothe detection area DA. Namely, the five intermediate images Ir1-Ir5elongated in an oblique direction at 45° to the X-direction and theY-direction are formed at a predetermined pitch along the X-direction,corresponding to the light-sending slits Sr1-Sr5, in the detection areaDA. The intermediate images Ir1-Ir5 of the reference pattern herein arefowled so that their centers agree with the respective centers of theintermediate images Im1-Im5. In other words, the light-sending slitsSm1-Sm5 and the light-sending slits Sr1-Sr5 are formed so that centersof corresponding element patterns of the intermediate images formed inthe detection area DA agree with each other.

As described above, the dichroic mirror 4, second objective lens 5,vibrating mirror 6, first objective lens 7, rhombic prism 8, dichroicfilm 9, angle-deviating prism 10, and reflecting prism 11 constitute alight-sending optical system which makes the measurement light (firstlight) from the light-sending slits Sm1-Sm5 and the reference light(second light) from the light-sending slits Sr1-Sr5 incident at themutually different incidence angles θm and θr, respectively, to thephotosensitive surface Wa to project the intermediate images Im1-Im5 ofthe measurement pattern and the intermediate images Ir1-Ir5 of thereference pattern onto the detection area DA on the photosensitivesurface Wa.

The light-sending optical system makes the intermediate images Im1-Im5of the measurement pattern and the intermediate images Ir1-Ir5 of thereference pattern arrayed in the same row along the plane of incidenceof the measurement light to the photosensitive surface Wa. The elementpatterns of the intermediate images Im1-Im5 of the measurement patternare arrayed at the same locations on the photosensitive surface Wa asthe corresponding element patterns of the intermediate images Ir1-Ir5 ofthe reference pattern are.

The second objective lens 5, vibrating mirror 6, first objective lens 7,and rhombic prism 8 constitute sending-side common optical membersprovided in common to the measurement light and the reference light. Thereflecting prism 11 constitutes a sending-side reflecting section whichreflects the reference light having traveled via the sending-side commonoptical members (5-8), twice to make the reference light incident at theincidence angle smaller than that of the measurement light, to thephotosensitive surface Wa. The dichroic film 9 and angle-deviating prism10 constitute a sending-side deflecting section which deflects themeasurement light and the reference light having traveled via thesending-side common optical members (5-8), relative to each other toguide the measurement light to the photosensitive surface Wa and guidethe reference light to the reflecting prism 11.

The dichroic mirror 4 constitutes a sending-side combining section whichguides the measurement light and the reference light incident frommutually different directions, to the sending-side common opticalmembers (5-8). The reflecting prism 11 is arranged immediately above thephotosensitive surface Wa, specifically, immediately above theintermediate images Ir1-Ir5 of the reference pattern on thephotosensitive surface Wa. The dichroic film 9 constitutes asending-side separating surface which reflects the measurement light andtransmits the reference light, depending upon the wavelengths of themeasurement light and the reference light. The sending-side separatingsurface can also be configured so as to reflect the measurement lightand transmit the reference light, depending upon polarizations of themeasurement light and the reference light.

With reference to FIG. 5, the measurement light Lm reflected by thephotosensitive surface Wa is incident into the rhombic prism 28. Therhombic prism 28 is arranged at a position in symmetry with the rhombicprism 8 and has a symmetrical configuration therewith respect to thepredetermined YZ plane (e.g., the YZ plane including the optical axisAX). Specifically, the rhombic prism 28 has a configuration obtained byinverting the rhombic prism 8 with respect to the entrance face 8 a. Adichroic film 29 is formed on a lower side face 28 b in the drawing ofthe rhombic prism 28 and the angle-deviating prism 30 is attached inproximity to this dichroic film 29.

The dichroic film 29 and the angle-deviating prism 30 are arranged atrespective positions in symmetry with the dichroic film 9 and theangle-deviating prism 10, respectively, and have their respectiveconfigurations symmetrical therewith respect to the predetermined YZplane (e.g., the YZ plane including the optical axis AX). The dichroicfilm 29 has the same characteristic as the dichroic film 9, as to theseparating action of light depending upon wavelengths. Therefore, themeasurement light Lm incident through an entrance face 28 a of therhombic prism 28 is successively reflected by the dichroic film 29 andreflecting face 28 c and thereafter is emitted from an exit face 28 d.

On the other hand, the reference light Lr reflected by thephotosensitive surface Wa is incident into a reflecting prism 31 of aprismatic shape extending in the Y-direction. The reflecting prism 31 isarranged at a position in symmetry with the reflecting prism 11 and hasa configuration symmetrical therewith respect the predetermined YZ plane(e.g., the YZ plane including the optical axis AX). Therefore, thereference light Lr incident into the reflecting prism 31 is successivelyreflected by its reflecting faces 31 a and 31 b, is emitted obliquelydownward in the drawing from the reflecting prism 31, and thereafter isincident into the rhombic prism 28.

The reference light Lr incident into the rhombic prism 28 travelssuccessively through the entrance face 28 a thereof and the dichroicfilm 29 to enter the angle-deviating prism 30. The reference light Lrentering the angle-deviating prism 30 is reflected by its reflectingface 30 a, travels through the dichroic film 29, is reflected by thereflecting face 28 c, and thereafter is emitted from the exit face 28 d.The reference light Lr emitted from the exit face 28 d is guided alongthe same optical path as the measurement light Lm, to the subsequentfirst objective lens 27 (not shown in FIG. 5).

With reference to FIGS. 1 and 2, the measurement light emitted from therhombic prism 28 travels via the first objective lens 27, mirror (notshown in FIG. 2) 26, and second objective lens 25, and then istransmitted by the dichroic mirror (not shown in FIG. 1) 24 to enter thelight-receiving prism 23A. The reference light emitted from the rhombicprism 28 travels via the first objective lens 27, mirror 26, and secondobjective lens 25 and thereafter is reflected by the dichroic mirror 24to enter the light-receiving prism 23B.

The first objective lens 27, mirror 26, second objective lens 25, anddichroic mirror 24 are arranged at positions in symmetry with the firstobjective lens 7, vibrating mirror 6, second objective lens 5, anddichroic mirror 4, respectively, and have configurations symmetricaltherewith respect to the predetermined YZ plane (e.g., the YZ planeincluding the optical axis AX). However, the mirror 26, different fromthe vibrating mirror 6, is fixedly installed. The dichroic mirror 24 hasthe same characteristic as the dichroic mirror 4, as to the separatingaction of light depending upon wavelengths.

The light-receiving prisms 23A and 23B are arranged at positions insymmetry with the light-sending prisms 3A and 3B, respectively, and haverespective configurations symmetrical therewith respect to thepredetermined YZ plane (e.g., the YZ plane including the optical axisAX). Five light-receiving slits Sma1, Sma2, Sma3, Sma4, and Sma5corresponding to the light-sending slits Sm1-Sm5 are provided, as shownin FIG. 8, on an entrance face 23Aa (face corresponding to the exit face3Aa of the light-sending prism 3A) of the light-receiving prism 23A formeasurement light. In FIG. 8, a y3-axis is set along a directionparallel to the Y-axis of the global coordinate system on the entranceface 23Aa and an x3-axis is set along a direction perpendicular to they3-axis on the entrance face 23Aa.

Five light-receiving slits Sra1, Sra2, Sra3, Sra4, and Sra5corresponding to the light-sending slits Sr1-Sr5 are provided, as shownin FIG. 9, on an entrance face 23Ba (face corresponding to the exit face3Ba of the light-sending prism 3B) of the light-receiving prism 23B forreference light. In FIG. 9, a y4-axis is set along a direction parallelto the Y-axis of the global coordinate system on the entrance face 23Baand an x4-axis is set along a direction perpendicular to the y4-axis onthe entrance face 23Ba.

The light-receiving slits Sma1-Sma5 are optically transparent portionsof a rectangular shape (slit shape) elongated in an oblique direction at45° to the x3-direction and the y3-direction and the region other thanthe light-receiving slits Sma1-Sma5 is a light shield portion. Thelight-receiving slits Sra1-Sra5 are optically transparent portions of arectangular shape (slit shape) elongated in an oblique direction at 45°to the x4-direction and the y4-direction and the region other than thelight-receiving slits Sra1-Sra5 is a light shield portion. Thelight-receiving slits Sma1-Sma5 are arrayed at a predetermined pitchalong the x3-direction (e.g., a pitch equal to that of the light-sendingslits Sm1-Sm5) and the light-receiving slits Sra1-Sra5 are arrayed at apredetermined pitch along the x4-direction (e.g., a pitch equal to thatof the light-sending slits Sr1-Sr5).

Observation images of the light-sending slits Sm1-Sm5 for measurementlight are formed on the entrance face 23Aa of the light-receiving prism23A and observation images of the light-sending slits Sr1-Sr5 forreference light are formed on the entrance face 23Ba of thelight-receiving prism 23B. Namely, five element patterns of theslit-like observation images elongated in an oblique direction at 45° tothe x3-direction and the y3-direction are formed at a predeterminedpitch along the x3-direction, corresponding to the light-sending slitsSm1-Sm5, on the entrance face 23Aa. Five element patterns of theslit-like observation images elongated in an oblique direction at 45° tothe x4-direction and the y4-direction are formed at a predeterminedpitch along the x4-direction, corresponding to the light-sending slitsSr1-Sr5, on the entrance face 23Ba.

As described above, the reflecting prism 31, angle-deviating prism 30,dichroic film 29, rhombic prism 28, first objective lens 27, mirror 26,second objective lens 25, and dichroic mirror 24 constitute alight-receiving optical system which guides the measurement light andthe reference light reflected by the photosensitive surface Wa, to theentrance face 23Aa (first observation surface) and to the entrance face23Ba (second observation surface), respectively, to form the observationimage of the measurement pattern on the entrance face 23Aa and theobservation image of the reference pattern on the entrance face 23Ba.

The rhombic prism 28, first objective lens 27, mirror 26, and secondobjective lens 25 constitute receiving-side common optical membersprovided in common to the measurement light and the reference lightreflected by the photosensitive surface Wa. The reflecting prism 31constitutes a receiving-side reflecting section which reflects thereference light reflected by the photosensitive surface Wa, twice toguide the reference light to the receiving-side common optical members(28-25). The angle-deviating prism 30 and dichroic film 29 constitute areceiving-side deflecting section which deflects the measurement lighthaving been reflected by the photosensitive surface Wa and the referencelight having traveled through the reflecting prism 31, relative to eachother to guide the measurement light and the reference light to thereceiving-side common optical members (28-25).

The dichroic mirror 24 constitutes a receiving-side separating sectionwhich causes relative deflection between the measurement light and thereference light having traveled via the receiving-side common opticalmembers (28-25), to guide the measurement light to the entrance face23Aa and the reference light to the entrance face 23Ba. The dichroicfilm 29 constitutes a receiving-side combining surface which reflectsthe measurement light and transmits the reference light, depending uponthe wavelengths of the measurement light and the reference light. Thereceiving-side combining surface can also be configured so as to reflectthe measurement light and transmit the reference light, depending uponpolarizations of the measurement light and the reference light.

The measurement light entering the light-receiving prism 23A travelsthrough the light-receiving slits Sma1-Sma5 to be deflected by apredetermined angle and is emitted from the light-receiving prism 23A.The measurement light emitted from the light-receiving prism 23A travelsthrough the relay lens 22A to form a conjugate image of the observationimage of the measurement pattern formed in the respectivelight-receiving slits Sma1-Sma5, on a detection surface 21Aa of aphotodetector 21A.

Five light-receiving portions RSm1-RSm5 are provided so as to correspondto the five light-receiving slits Sma1-Sma5 for measurement light, asshown in FIG. 10, on the detection surface 21Aa of the photodetector21A. The five light-receiving portions RSm1-RSm5 receive respectivemeasurement light beams having passed through the five light-receivingslits Sma1-Sma5 corresponding to the light-sending slits Sm1-Sm5. Therespective element patterns of the observation images of thelight-sending slits Sm1-Sm5 move in the x3-direction on the entranceface 23Aa with movement of the photosensitive surface Wa along theZ-direction. Therefore, light quantities of the measurement light beamsthrough the light-receiving slits Sma1-Sma5 vary according to theZ-directional movement of the photosensitive surface Wa.

Similarly, the reference light entering the light-receiving prism 23Btravels through the light-receiving slits Sra1-Sra5 to be deflected by apredetermined angle and thereafter is emitted from the light-receivingprism 23B. The reference light emitted from the light-receiving prism23B travels through the relay lens 22B to form a conjugate image of theobservation image of the reference pattern formed in the respectivelight-receiving slits Sra1-Sra5, on a detection surface 21Ba of aphotodetector 21B.

Five light-receiving portions RSr1-RSr5 are provided so as to correspondto the five light-receiving slits Sra1-Sra5 for measurement light, asshown in FIG. 11, on the detection surface 21Ba of the photodetector21B. The five light-receiving portions RSr1-RSr5 receive respectivereference light beams having passed through the five light-receivingslits Sra1-Sra5 corresponding to the light-sending slits Sr1-Sr5. Therespective element patterns of the observation images of thelight-sending slits Sr1-Sr5 move in the x4-direction on the entranceface 23Ba with movement of the photosensitive surface Wa along theZ-direction. Therefore, light quantities of the reference light beamsthrough the light-receiving slits Sra1-Sra5 also vary according to theZ-directional movement of the photosensitive surface Wa as in the caseof the measurement light beams.

The surface position detecting apparatus of the first embodiment exampleis so configured that, in a state in which the photosensitive surface Wais aligned with the image plane of the projection optical system PL, therespective element patterns of the observation images of thelight-sending slits Sm1-Sm5 (observation image of the measurementpattern) are formed at the positions of the light-receiving slitsSma1-Sma5 and the respective element patterns of the observation imagesof the light-sending slits Sr1-Sr5 (observation image of the referencepattern) are formed at the positions of the light-receiving slitsSra1-Sra5. Detection signals of the light-receiving portions RSm1-RSm5and detection signals of the light-receiving portions RSr1-RSr5 vary insynchronism with vibration of the vibrating mirror 6 and are supplied tothe signal processor PR.

As described above, when the photosensitive surface Wa vertically movesin the Z-direction along the optical axis AX of the projection opticalsystem PL, the respective element patterns in the observation image ofthe measurement pattern formed on the entrance face 23Aa of thelight-receiving prism 23A come to have a positional deviation in thepitch direction (x3-direction) corresponding to the vertical movement ofthe photosensitive surface Wa. Similarly, the respective elementpatterns in the observation image of the reference pattern formed on theentrance face 23Ba of the light-receiving prism 23B come to have apositional deviation in the pitch direction (x4-direction) correspondingto the vertical movement of the photosensitive surface Wa.

The signal processor PR detects positional deviation amounts (positioninformation) of the respective element patterns in the observation imageof the measurement pattern based on outputs from the photodetector 21A,for example, according to the principle of the photoelectric microscopedisclosed in Japanese Patent Application Laid-open No. 6-97045 filed bythe same applicant, and calculates surface positions (Z-directionalpositions) Zm1-Zm5 of the respective detection points in the detectionarea DA, based on the detected positional deviation amounts. Similarly,the signal processor PR detects positional deviation amounts of therespective element patterns in the observation image of the referencepattern based on outputs from the photodetector 21B and calculatessurface positions Zr1-Zr5 of the respective detection points in thedetection area DA, based on the detected positional deviation amounts.In this case, the slit widths of the light-sending slits Sm1-Sm5,Sr1-Sr5 and the light-receiving slits Sma1-Sma5, Sra1-Sra5, theamplitude of the vibration of the vibrating mirror 6 (angular range ofrocking motion around the Y-axis), etc. are set so as to enable thedetection of position information based on the principle of thephotoelectric microscope concurrently for the measurement light and thereference light.

As described previously, the positions of the respective elementpatterns in the measurement pattern observation image formed on theentrance face 23Aa of the light-receiving prism 23A can have apositional deviation from the positions of the respectivelight-receiving slits Sma1-Sma5, for example, even if the photosensitivesurface Wa is aligned with the image plane of the projection opticalsystem PL (or is in a best focus condition), because of variation inposition, variation in refractive index, etc. of an optical memberforming the surface position detecting apparatus. In this case, thesurface positions Zm1-Zm5 of the respective detection points willinclude a detection error, depending upon positional deviation amountsof the respective element patterns in the measurement patternobservation image from the light-receiving slits Sma1-Sma5.

For the same reason, the positions of the respective element patterns inthe reference pattern observation image formed on the entrance face 23Baof the light-receiving prism 23B can have a positional deviation fromthe positions of the respective light-receiving slits Sra1-Sra5 even ifthe photosensitive surface Wa is aligned with the image plane of theprojection optical system PL. In this case, the surface positionsZr1-Zr5 of the respective detection points will include a detectionerror, depending upon positional deviation amounts of the respectiveelement patterns in the reference pattern observation image from thelight-receiving slits Sra1-Sra5.

In the surface position detecting apparatus of the first embodimentexample, the measurement light from the light-sending slits Sm1-Sm5 andthe reference light from the light-sending slits Sr1-Sr5 travels via theplurality of optical members common to the measurement light and thereference light, i.e., via the sending-side common optical members (5-8)and the receiving-side common optical members (28-25) to form theobservation image of the measurement pattern and the observation imageof the reference pattern, respectively. Therefore, the observation imageof the reference pattern includes information about influence ofvariation in the sending-side common optical members (5-8) and thereceiving-side common optical members (28-25) as the observation imageof the measurement light does.

In other words, the surface positions Zm1-Zm5 calculated based on theposition information of the observation image of the measurement patternand the surface positions Zr1-Zr5 calculated in the same manner as themeasurement light, based on the position information of the observationimage of the reference pattern contain a common detection error ofsurface position due to the sending-side common optical members (5-8)forming the major part of the light-sending optical system and thereceiving-side common optical members (28-25) forming the major part ofthe light-receiving optical system. In the description hereinafter, asurface position to be detected with the measurement light without anyinfluence of variation in an optical member will be called “true surfaceposition.”

The following relations represented by Eq (1) and Eq (2) below holdamong the true surface position Zv, the first surface position Zmcalculated based on the position information of the observation image ofthe measurement pattern, and the second surface position Zr calculatedbased on the position information of the observation image of thereference pattern.Zm=Zv+Eo  (1)Zr=(sin θr/sin θm)×Zv+Eo  (2)

In Eqs (1) and (2), Eo is a detection error of surface position due tovariation in an optical member and common error included in the surfaceposition Zm based on the position information of the observation imageof the measurement pattern and in the surface position Zr based on theposition information of the observation image of the reference pattern.θm is the incidence angle of the measurement light to the photosensitivesurface Wa and θr the incidence angle of the reference light to thephotosensitive surface Wa. In the first embodiment example, α=sin θr/sinθm is smaller than 1 because the incidence angle θm of the measurementlight is set to be larger than the incidence angle θr of the referencelight. By solving Eqs (1) and (2) for the true surface position Zv, weobtain the following relation represented by Eq (3) below.Zv=(Zm−Zr)/(1−sin θr/sin θm)  (3)

In the first embodiment example, the signal processor PR calculates thesurface positions Zm1-Zm5, based on the position information of therespective element patterns in the observation image of the measurementpattern and calculates the surface positions Zr1-Zr5, based on theposition information of the respective element patterns in theobservation image of the reference pattern. Then the signal processor PRcalculates the surface position Zv, for example, obtained bysubstituting surface positions Zmi and Zri calculated for the i-th(i=1-5) element pattern, as the surface positions Zm and Zr into Eq (3),as a corrected surface position Zvi free of influence of variation inthe optical members.

Namely, the signal processor PR calculates corrected surface positionsZv1-Zv5 at the respective detection points in the detection area DA,based on the surface positions Zm1-Zm5 associated with the measurementlight and the surface positions Zr1-Zr5 associated with the referencelight. The calculation results are fed, for example, to a storagesection MR provided inside the controller CR of the exposure apparatus.The controller CR supplies a command to the driving system HD, asneeded, to move the XY stage HS and, therefore, the wafer W along the XYplane. Then the surface position detecting apparatus calculates thecorrected surface positions Zv1-Zv5 at respective detection points in anew detection area DA on the photosensitive surface Wa of the wafer Wand feeds the calculation results to the storage section MR.

In other words, the surface position detecting apparatus detects thesurface positions at plural locations on the photosensitive surface Wa,according to movement of the XY stage HS in a direction along thephotosensitive surface Wa and, therefore, according to movement of theZ-stage VS in a direction along the photosensitive surface Wa by thedriving system HD as a plane driving mechanism. The sequentialprocessing consisting of the movement of the wafer W along the XY planeand the calculation of corrected surface positions Zv1-Zv5 is carriedout a required number of times across a required range as occasion maydemand. A plurality of detection results (i.e., information aboutcorrected surface positions at a plurality of detection points) by thesurface position detecting apparatus are stored in the form of map datain the storage section MR.

Thereafter, the controller CR adjusts the Z-directional position of theZ-stage VS by a required amount in accordance with a position of the XYstage HS and Z-stage VS along the photosensitive surface Wa, based onthe detection results obtained by the signal processor PR and,therefore, based on the map data of surface positions stored in thestorage section MR, to align a detection area on the photosensitivesurface Wa, i.e., a current exposure region on the wafer W with theimage plane position (best focus position) of the projection opticalsystem PL. Specifically, the controller CR supplies a command to thedriving system VD as a vertical driving mechanism according to thecurrent exposure region to move the Z-stage VS and, therefore, the waferW along the Z-direction normal to the photosensitive surface Wa by arequired amount.

As described above, the light-receiving prisms 23A, 23B, relay lenses22A, 22B, photodetectors 21A, 21B, and signal processor PR constitute adetecting section which detects the position information of theobservation images of the light-sending slits Sm1-Sm5 on the entranceface 23Aa of the light-receiving prism 23A and the position informationof the observation images of the light-sending slits Sr1-Sr5 on theentrance face 23Ba of the light-receiving prism 23B and which calculatesthe surface position of the photosensitive surface Wa (or the correctedsurface position Zvi) based on the position information thus detected.

In the surface position detecting apparatus of the first embodimentexample, as described above, the observation image of the measurementpattern contains the information about influence of variation in theoptical members common to the measurement light and the reference lightas the observation image of the reference pattern does. Namely, thesurface position Zm calculated based on the position information of theobservation image of the measurement pattern and the surface position Zrcalculated based on the position information of the observation image ofthe reference pattern contain the common detection error Eo of thesurface position due to the variation in the optical members.

Therefore, the surface position detecting apparatus of the firstembodiment example is able to calculate the corrected surface positionZv substantially free of the influence of variation in the opticalmembers, using the surface position Zm calculated based on themeasurement light and the surface position Zr calculated based on thereference light, or able to highly accurately detect the surfaceposition of the photosensitive surface Wa without being affected by thevariation in the optical members.

Furthermore, the surface position detecting apparatus of the firstembodiment example is provided with the reflecting prism 11 whichreflects the reference light having passed via the sending-side commonoptical members (5-8), twice by its reflecting faces 11 a and 11 b tomake the reference light incident to the photosensitive surface Wa, andthe reflecting prism 31 which reflects the reference light reflected bythe photosensitive surface Wa, twice by its reflecting faces 31 a and 31b to guide the reference light to the receiving-side common opticalmembers (28-25). Namely, the reflecting face 11 a and the reflectingface 11 b are integrally formed in the reflecting prism 11 being asingle optical member, and the reflecting face 31 a and the reflectingface 31 b are integrally formed in the reflecting prism 31 being asingle optical member.

Therefore, for example, even in a case where there is a variation in theposture of the reflecting prism 11 as the sending-side reflectingsection and/or in the posture of the reflecting prism 31 as thereceiving-side reflecting section due to influence of vibration of theapparatus, there occurs no variation in the angle between the reflectingface 11 a and the reflecting face 11 b and in the angle between thereflecting face 31 a and the reflecting face 31 b. This means that thereis no variation in the angle between the reference light incident intothe reflecting prism 11 and the reference light emerging from thereflecting prism 11 and in the angle between the reference lightincident into the reflecting prism 31 and the reference light emergingfrom the reflecting prism 31.

As a consequence, the surface position detecting apparatus of the firstembodiment example is able to stably maintain the incidence angle of thereference light to the photosensitive surface Wa at the desired angleand eventually to highly accurately detect the surface position of thephotosensitive surface Wa, without being affected by variation in thereflecting prism 11 disposed in the reference optical path between thesending-side common optical members (5-8) and the photosensitive surfaceWa. Furthermore, the surface position detecting apparatus of the firstembodiment example is able to stably maintain the incidence angle of thereference light to the entrance face 23Ba (second observation face) ofthe light-receiving prism 23B at the desired angle and eventually tohighly accurately detect the surface position of the photosensitivesurface Wa, without being affected by variation in the reflecting prism31 disposed in the reference optical path between the photosensitivesurface Wa and the receiving-side common optical members (28-25).

In this manner, the exposure apparatus of the present embodiment is ableto highly accurately detect the surface position of the photosensitivesurface Wa of the wafer W and, therefore, to highly accurately align thephotosensitive surface Wa with the image plane of the projection opticalsystem PL corresponding to the pattern surface of the reticle R.

In the above description, the apparatus is constructed by adopting theconfiguration wherein the measurement light is transmitted by thedichroic mirrors 4, 24 and the reference light is reflected by thedichroic mirrors 4, 24. Furthermore, the above embodiment example adoptsthe configuration wherein the measurement light is reflected by thedichroic films 9, 29 and the reference light is transmitted by thedichroic films 9, 29. It is, however, possible to adopt a configurationwherein the dichroic mirrors 4, 24 reflect the measurement light andtransmit the reference light or a configuration wherein the dichroicfilms 9, 29 transmit the measurement light and reflect the referencelight, according to arrangement of the optical members in thelight-sending optical system and in the light-receiving optical systemwith respect to the wafer W.

In the above description, the dichroic mirrors 4, 24 transmit themeasurement light and reflect the reference light, depending upon thewavelengths of the measurement light and the reference light.Furthermore, the dichroic films 9, 29 reflect the measurement light andtransmit the reference light, depending upon the wavelengths of themeasurement light and the reference light. However, the dichroic mirrors4, 24 may be replaced by polarization beam splitters which reflect oneof the measurement light and the reference light and transmit the other,depending upon polarization states of the measurement light and thereference light. Furthermore, the dichroic films 9, 29 may be replacedby polarization separating films which reflect one of the measurementlight and the reference light and transmit the other, depending uponpolarization states of the measurement light and the reference light.

FIG. 12 is a drawing showing a configuration of the surface positiondetecting apparatus according to a second embodiment example. The secondembodiment example has the configuration similar to that of the firstembodiment example. However, the second embodiment example is differentfrom the first embodiment example in that the row of element patterns inthe intermediate image of the measurement pattern and the row of elementpatterns in the intermediate image of the reference pattern are arrayedin parallel with a space between them. The configuration and action ofthe second embodiment example will be described below with focus on thedifference from the first embodiment example.

The surface position detecting apparatus of the second embodimentexample has a light source 1 and a condenser lens 2 as a commonillumination system to the light-sending prism 3A for measurement lightand the light-sending prism 3B for reference light. The light-sendingprism 3A and the light-sending prism 3B are arranged in proximity toeach other as separate optical members. Alternatively, the light-sendingprism 3A and the light-sending prism 3B are formed integrally as oneoptical member. It should be noted that the light-sending prism 3A andthe light-sending prism 3B may be illuminated by separate illuminationsystems.

The measurement light having passed through the light-sending slitsSm1-Sm5 (cf. FIG. 3) provided on an exit face 3Aa of the light-sendingprism 3A, travels via the second objective lens 5, vibrating mirror 6,and first objective lens 7 to enter the rhombic prism 8. The referencelight having passed through the light-sending slits Sr1-Sr5 (cf. FIG. 4)provided on an exit face 3Ba (which is a face not flush with the exitface 3Aa) of the light-sending prism 3B, travels along an optical pathseparated with a space in the Y-direction from the optical path of themeasurement light and via the second objective lens 5, vibrating mirror6, and first objective lens 7 to enter the rhombic prism 8.

In the second embodiment example, as described above, there is nodichroic mirror arranged in the optical path between the light-sendingprisms 3A, 3B and the second objective lens 5, different from the firstembodiment example. In the second embodiment example, different from thefirst embodiment example, there is no dichroic film formed on the lowerside face in the drawing of the rhombic prism 8. In the secondembodiment example, as shown in FIGS. 13 and 14, the angle-deviatingprism 10 is attached in proximity to the lower side face in the drawingof the rhombic prism 8 and in a region corresponding to the optical pathof reference light Lr.

With reference to FIGS. 13 and 14, the measurement light Lm incidentalong the measurement optical path indicated by a solid line, to theentrance face 8 a of the rhombic prism 8 is successively reflected bythe reflecting face 8 b and side face 8 c and thereafter is emitted fromthe exit face 8 d. The measurement light Lm emitted from the exit face 8d is obliquely incident at the incidence angle θm along the XZ plane tothe detection area DA on the photosensitive surface Wa. On the otherhand, the reference light Lr entering the entrance face 8 a of therhombic prism 8 along the reference optical path (indicated by a dashedline in the drawing) separated with the space in the Y-direction fromthe measurement optical path is reflected by the reflecting face 8 b toenter the angle-deviating prism 10.

The reference light Lr entering the angle-deviating prism 10 isreflected by the reflecting face 10 a and is emitted obliquely upward inFIG. 13 from the exit face 8 d of the rhombic prism 8. The referencelight Lr emitted from the exit face 8 d is successively reflected by thereflecting faces 11 a and 11 b of the reflecting prism 11 and then isobliquely incident at the incidence angle θr to an area DB adjacent tothe detection area DA, along a plane parallel to the plane of incidenceof the measurement light Lm to the photosensitive surface Wa.

In this manner, five intermediate images Im1-Im5 elongated in an obliquedirection at 45° to the X-direction and the Y-direction are formed at apredetermined pitch along the X-direction, corresponding to thelight-sending slits Sm1-Sm5 as a measurement pattern, as schematicallyshown in FIG. 15, in the detection area DA on the photosensitive surfaceWa. The centers of the respective intermediate images Im1-Im5 correspondto predetermined detection points in the detection area DA. Similarly,five intermediate images Ir1-Ir5 elongated in an oblique direction at45° to the X-direction and the Y-direction are formed at a predeterminedpitch along the X-direction, corresponding to the light-sending slitsSr1-Sr5 as a reference pattern, in the area DB adjacent to the detectionarea DA on the photosensitive surface Wa.

Namely, the intermediate images Im1-Im5 of the measurement pattern andthe intermediate images Ir1-Ir5 of the reference pattern are formed inparallel with each other with the space in the Y-direction. TheX-directional pitch of the intermediate images Im1-Im5 of themeasurement pattern is equal to the X-directional pitch of theintermediate images Ir1-Ir5 of the reference pattern. In other words,the light-sending slits Sm1-Sm5 and the light-sending slits Sr1-Sr5 areformed so that the X-directional pitches of the element patterns of theintermediate images formed on the photosensitive surface Wa are equal toeach other. The intermediate image Im1 of the measurement pattern andthe intermediate image Ir1 of the reference pattern are arrangedadjacent to each other along the Y-direction and, similarly, the otherintermediate images Im2-Im5 of the measurement pattern are arrangedadjacent along the Y-direction to the intermediate images Ir2-Ir5 of thereference pattern, respectively.

The measurement light Lm reflected by the photosensitive surface Wa isthen incident into the rhombic prism 28. No dichroic film is formed onthe lower side face in FIG. 13 of the rhombic prism 28. Theangle-deviating prism 30 is attached in proximity to the lower side facein FIG. 13 of the rhombic prism 28 and in a region corresponding to theoptical path of reference light Lr. Therefore, the measurement light Lmincident through the entrance face 28 a of the rhombic prism 28 issuccessively reflected by the reflecting face 28 b and the side face 28c and thereafter is emitted from the exit face 28 d.

On the other hand, the reference light Lr reflected by thephotosensitive surface Wa is successively reflected by the reflectingfaces 31 a and 31 b of the reflecting prism 31 and travels through theentrance face 28 a of the rhombic prism 28 to enter the angle-deviatingprism 30. The reference light Lr entering the angle-deviating prism 30is reflected by the reflecting face 30 a, is then reflected by thereflecting face 28 c, and thereafter is emitted from the exit face 28 d.The reference light Lr emitted from the exit face 28 d is guided alongthe optical path separated with the space in the Y-direction from theoptical path of the measurement light Lm, to the first objective lens27.

The measurement light and the reference light emitted from the rhombicprism 28 travels via the first objective lens 27, mirror 26, and secondobjective lens 25 to enter a light-receiving prism 23A and alight-receiving prism 23B, respectively. Namely, no dichroic mirror isarranged in the optical path between the second objective lens 25 andthe light-receiving prisms 23A and 23B. The light-receiving prism 23Aand the light-receiving prism 23B are arranged in proximity to eachother as separate optical members. Alternatively, the light-receivingprism 23A and the light-receiving prism 23B are formed integrally as oneoptical member.

Observation images of the light-sending slits Sm1-Sm5 for measurementlight are formed on an entrance face 23Aa of the light-receiving prism23A. Observation images of the light-sending slits Sr1-Sr5 for referencelight are formed on an entrance face 23Ba (which is a face not flushwith the entrance face 23Aa) of the light-receiving prism 23B. Themeasurement light having passed through the light-receiving slitsSma1-Sma5 (cf. FIG. 8) provided on the entrance face 23Aa of thelight-receiving prism 23A, travels through a relay lens 22 to for in aconjugate image of the observation image of the measurement pattern on adetection surface 21 a of a photodetector 21.

The reference light having passed through the light-receiving slitsSra1-Sra5 (cf. FIG. 9) provided on the entrance face 23Ba of thelight-receiving prism 23B, travels through the relay lens 22 common tothe measurement light, to form a conjugate image of the observationimage of the reference pattern on the detection surface 21 a of thephotodetector 21 common to the measurement light. It can also becontemplated that the measurement light beam from the light-receivingprism 23A and the reference light beam from the light-receiving prism23B are guided through separate relay lenses 22A and 22B to separatephotodetectors 21A and 21B.

On the detection surface 21 a of the photodetector 21, as shown in FIG.16, there are light-receiving portions RSm1-RSm5 provided correspondingto the light-receiving slits Sma1-Sma5 for measurement light andlight-receiving portions RSr1-RSr5 provided corresponding to thelight-receiving slits Sra1-Sra5 for reference light. The light-receivingportions RSm1-RSm5 receive respective measurement light beams havingpassed through the light-receiving slits Sma1-Sma5 corresponding to thelight-sending slits Sm1-Sm5. The light-receiving portions RSr1-RSr5receive respective reference light beams having passed through thelight-receiving slits Sra1-Sra5 corresponding to the light-sending slitsSr1-Sr5.

In the second embodiment example, just as in the case of the firstembodiment example, the light quantities of the measurement light beamsthrough the light-receiving slits Sma1-Sma5 and the light quantities ofthe reference light beams through the light-receiving slits Sra1-Sra5also vary according to the Z-directional movement of the photosensitivesurface Wa. The detection signals of the light-receiving portionsRSm1-RSm5 and the detection signals of the light-receiving portionsRSr1-RSr5 vary in synchronism with the vibration of the vibrating mirror6 and are supplied to the signal processor PR.

In the second embodiment example, the signal processor PR calculates thesurface positions Zm1-Zm5, based on the position information of therespective element patterns in the observation image of the measurementpattern. Next, the controller CR supplies a command to the drivingsystem HD to move the XY stage HS (and, therefore, the wafer W) by arequired amount in the Y-direction, for example, so that the respectiveelement patterns in the intermediate image of the reference pattern areformed as centered at or near the respective detection points of thesurface positions Zm1-Zm5 (the centers of the respective elementpatterns in the intermediate image of the measurement pattern).

The signal processor PR calculates the surface positions Zr1-Zr5, basedon the position information of the respective element patterns in theobservation image of the reference pattern in a state in which thecenter of each element pattern in the intermediate image of thereference pattern agrees approximately with each detection point. Thenthe signal processor PR calculates the corrected surface positionsZv1-Zv5 at the respective detection points in the detection area DA,based on these surface positions Zr1-Zr5 associated with the referencelight and the already calculated surface positions Zm1-Zm5 associatedwith the measurement light. The calculation results are fed to thestorage section MR provided inside the controller CR.

The sequential processing consisting of the calculation of surfacepositions Zm1-Zm5 associated with the measurement light, the movement ofthe wafer W in the Y-direction, the calculation of surface positionsZr1-Zr5 associated with the reference light, and the calculation ofcorrected surface positions Zv1-Zv5 is carried out a predeterminednumber of times as needed. A plurality of detection results (or theinformation about the corrected surface positions at a plurality ofdetection points) by the surface position detecting apparatus are storedin the form of map data in the storage section MR. It is noted that thesignal processor PR may be configured to calculate the surface positionsZr1-Zr5 associated with the reference light, based on the positioninformation of the respective element patterns in the observation imageof the reference pattern with the reference light reflected in the areaDB, and then obtain the surface positions Zv1-Zv5.

The controller CR adjusts the Z-directional position of the Z-stage VSby a required amount, based on the map data of the surface positionsstored in the storage section MR, to align the detection area on thephotosensitive surface Wa and, therefore, the current exposure region onthe wafer W with the image plane position of the projection opticalsystem PL. In this manner, the surface position detecting apparatus ofthe second embodiment example is also able to calculate the correctedsurface position Zv substantially free of the influence of variation inthe optical members, using the surface position Zm calculated based onthe measurement light and the surface position Zr calculated based onthe reference light, or able to highly accurately detect the surfaceposition of the photosensitive surface Wa without being affected by thevariation in the optical members.

The surface position detecting apparatus of the second embodimentexample is also able to highly accurately detect the surface position ofthe photosensitive surface Wa, without being affected by variation inthe reflecting prism 11 disposed in the reference optical path betweenthe sending-side common optical members (5-8) and the photosensitivesurface Wa and by variation in the reflecting prism 31 disposed in thereference optical path between the photosensitive surface Wa and thereceiving-side common optical members (28-25), as in the case of thefirst embodiment example.

FIG. 17 is a drawing showing a configuration of the surface positiondetecting apparatus according to a third embodiment example. The thirdembodiment example has a configuration similar to that of the secondembodiment example. However, the third embodiment example is differentfrom the second embodiment example in that the plane of incidence of thereference light to the photosensitive surface Wa intersects with theplane of incidence of the measurement light to the photosensitivesurface Wa. The configuration and action of the third embodiment examplewill be described below with focus on the difference from the secondembodiment example.

In the third embodiment example, just as in the second embodimentexample, the measurement light having passed through the light-sendingslits Sm1-Sm5 provided on the exit face 3Aa of the light-sending prism3A, also travels via the second objective lens 5, vibrating mirror 6,and first objective lens 7 to enter the rhombic prism 8. The referencelight having passed through the light-sending slits Sr1-Sr5 provided onthe exit face 3Ba of the light-sending prism 3B, travels along theoptical path separated with the space in the Y-direction from theoptical path of the measurement light and via the second objective lens5, vibrating mirror 6, and first objective lens 7 to enter the rhombicprism 8.

As shown in FIGS. 18 and 19, the measurement light Lm incident throughthe entrance face 8 a of the rhombic prism 8 along the measurementoptical path indicated by a solid line, is successively reflected by thereflecting face 8 b and the side face 8 c, is emitted from the exit face8 d, and thereafter is obliquely incident at the incidence angle θmalong the XZ plane to the detection area DA on the photosensitivesurface Wa. On the other hand, the reference light Lr incident throughthe entrance face 8 a of the rhombic prism 8 along the reference opticalpath (indicated by a dashed line in the drawing) separated with thespace in the Y-direction from the measurement optical path, is reflectedby the reflecting face 8 b, is reflected by the reflecting face 10 a ofthe angle-deviating prism 10, and thereafter is emitted obliquely upwardin FIG. 18 from the exit face 8 d of the rhombic prism 8.

The reference light Lr emitted from the exit face 8 d is incident into areflecting prism 12 having the action and form as shown in FIGS. 20 and21. FIG. 20 shows by the optical path of the reference light Lr a statein which the reference light Lr incident into the reflecting prism 12 isreflected twice to be guided to the photosensitive surface Wa, and astate in which the reference light Lr incident from the photosensitivesurface Wa into below-described reflecting prism 32 is reflected twiceto be guided into the rhombic prism 8. FIG. 21 shows a cross section ofthe reflecting prism 12 (32) along a plane including the reference lightLri incident into the reflecting prism 12 (32) and the reference lightLro emerging from the reflecting prism 12 (32).

Since the reflecting prisms 12 and 32 have the contour hard toillustrate and are arranged in the posture hard to illustrate, they aredepicted by a simple square in FIGS. 17-19. Referring to FIGS. 17-21,the reference light Lr emerging from the exit face 8 d of the rhombicprism 8 is incident into the reflecting prism 12, is successivelyreflected by its reflecting faces 12 a and 12 b, and is emitted from thereflecting prism 12. Thereafter, the reference light Lr is obliquelyincident at the incidence angle θr to the detection area DA and alongthe plane (YZ plane) perpendicular to the plane of incidence of themeasurement light Lm to the photosensitive surface Wa.

In this manner, as schematically shown in FIG. 7, five intermediateimages Im1-Im5 elongated in an oblique direction at 45° to theX-direction and the Y-direction are formed at a predetermined pitchalong the X-direction, corresponding to the light-sending slits Sm1-Sm5as the measurement pattern, in the detection area DA on thephotosensitive surface Wa, as in the case of the first embodimentexample. The centers of the respective intermediate images Im1-Im5correspond to predetermined detection points in the detection area DA.Furthermore, five intermediate images Ir1-Ir5 elongated in an obliquedirection to the X-direction and the Y-direction are formedcorresponding to the light-sending slits Sr1-Sr5 as the referencepattern, in the detection area DA.

In the third embodiment example, as described above, the plane ofincidence of the measurement light to the photosensitive surface Wa isorthogonal to the plane of incidence of the reference light to thephotosensitive surface Wa, different from the first embodiment example,and the incidence angle component of the reference light along the planeof incidence of the measurement light is 0°.

The measurement light Lm reflected by the photosensitive surface Watravels through the entrance face 28 a of the rhombic prism 28, issuccessively reflected by the side face 28 b and the reflecting face 28c, and thereafter is emitted from the exit face 28 d. On the other hand,the reference light Lr reflected by the photosensitive surface Wa isincident into the reflecting prism 32, is successively reflected by itsreflecting faces 32 a and 32 b, and is emitted from the reflecting prism32. The reference light Lr emitted from the reflecting prism 32 travelthrough the entrance face 28 a of the rhombic prism 28 to enter theangle-deviating prism 30. The reference light Lr incident into theangle-deviating prism 30 is reflected by its reflecting face 30 a,reflected by the reflecting face 28 c of the rhombic prism 28, and thenemitted from the exit face 28 d. The reference light Lr emitted from theexit face 28 d is guided along an optical path separated with the spacein the Y-direction from the optical path of the measurement light Lm, tothe first objective lens 27.

The measurement light and reference light emitted from the rhombic prism28 travels via the first objective lens 27, mirror 26, and secondobjective lens 25 to enter the light-receiving prism 23A and thelight-receiving prism 23B, respectively. Observation images of thelight-sending slits Sm1-Sm5 for measurement light are formed on theentrance face 23Aa of the light-receiving prism 23A and observationimages of the light-sending slits Sr1-Sr5 for reference light are formedon the entrance face 23Ba of the light-receiving prism 23B.

The measurement light having passed through the light-receiving slitsSma1-Sma5 provided on the entrance face 23Aa and the reference lighthaving passed through the light-receiving slits Sra1-Sra5 provided onthe entrance face 23Ba, travels through the relay lens 22 to form aconjugate image of the observation image of the measurement pattern anda conjugate image of the observation image of the reference pattern,respectively, on the detection surface 21 a of the photodetector 21.Light-receiving portions RSm1-RSm5 are provided so as to correspond tothe light-receiving slits Sma1-Sma5 for measurement light andlight-receiving portions RSr1-RSr5 are provided so as to correspond tothe light-receiving slits Sra1-Sra5 for reference light, on thedetection surface 21 a of the photodetector 21.

In the third embodiment example, just as in the first embodiment exampleand the second embodiment example, the light quantities of themeasurement light beams through the light-receiving slits Sma1-Sma5 andthe light quantities of the reference light beams through thelight-receiving slits Sra1-Sra5 vary according to the Z-directionalmovement of the photosensitive surface Wa. The detection signals of thelight-receiving portions RSm1-RSm5 and the detection signals of thelight-receiving portions RSr1-RSr5 vary in synchronism with thevibration of the vibrating mirror 6 and are fed to the signal processorPR.

In the third embodiment example, the signal processor PR calculates thesurface positions Zm1-Zm5, based on the position information of therespective element patterns in the observation image of the measurementpattern, and calculates the surface positions Zr1-Zr5, based on theposition information of the respective element patterns in theobservation image of the reference pattern. Then the signal processor PRcalculates corrected surface positions Zv1-Zv5 at the respectivedetection points in the detection area DA, based on the surfacepositions Zm1-Zm5 associated with the measurement light and the surfacepositions Zr1-Zr5 associated with the reference light. The sequentialprocessing consisting of the calculation of the surface positionsZm1-Zm5 associated with the measurement light, the calculation of thesurface positions Zr1-Zr5 associated with the reference light, and thecalculation of the corrected surface positions Zv1-Zv5 is carried out arequired number of times with movement of the wafer W along the XY planeas occasion may demand.

A plurality of detection results (or information about the correctedsurface positions at a plurality of detection points) by the surfaceposition detecting apparatus are stored in the form of map data in thestorage section MR. In this manner, the surface position detectingapparatus of the third embodiment example is also able to calculate thecorrected surface position Zv substantially free of the influence ofvariation in the optical members, using the surface position Zmcalculated based on the measurement light and the surface position Zrcalculated based on the reference light, or able to highly accuratelydetect the surface position of the photosensitive surface Wa withoutbeing affected by the variation in the optical members.

In the surface position detecting apparatus of the third embodimentexample, the reflecting face 12 a and the reflecting face 12 b, whichtwice reflect the reference light having passed via the sending-sidecommon optical members (5-8), are integrally formed in the reflectingprism 12, and the reflecting face 32 a and the reflecting face 32 b,which twice reflect the reference light having been reflected by thephotosensitive surface Wa, are integrally formed in the reflecting prism32. Therefore, the surface position detecting apparatus of the thirdembodiment example is also able to highly accurately detect the surfaceposition of the photosensitive surface Wa, without being affected byvariation in the reflecting prism 12 disposed in the reference opticalpath between the sending-side common optical members (5-8) and thephotosensitive surface Wa and by variation in the reflecting prism 32disposed in the reference optical path between the photosensitivesurface Wa and the receiving-side common optical members (28-25), as inthe first and second embodiment examples.

In the above description, the reflecting prism 11 or 12 with thereflecting faces 11 a, 11 b or 12 a, 12 b is used as the sending-sidereflecting section which twice reflects the reference light havingpassed via the sending-side common optical members (5-8), to guide thereference light to the photosensitive surface Wa. Furthermore, thereflecting prism 31 or 32 with the reflecting faces 31 a, 31 b or 32 a,32 b is used as the receiving-side reflecting section which twicereflects the reference light having been reflected by the photosensitivesurface Wa, to guide the reference light to the receiving-side commonoptical members (28-25).

Namely, in the foregoing configuration examples, the sending-sidereflecting section and the receiving-side reflecting section areconstructed as separate optical members. However, without having to belimited to this configuration, the sending-side reflecting section andthe receiving-side reflecting section may be integrally formed as oneoptical member. Specifically, in the configurations of the firstembodiment example and the second embodiment example, the reflectingprism 11 as the sending-side reflecting section and the reflecting prism31 as the receiving-side reflecting section may be integrated as shownin FIG. 22.

In the above configuration examples, the reflecting face (11 a, 12 a) asthe first reflecting surface and the reflecting face (11 b, 12 b) as thesecond reflecting surface are formed in the reflecting prism (11, 12)being a single optical member, and the reflecting face (31 a, 32 a) asthe third reflecting surface and the reflecting face (31 b, 32 b) as thefourth reflecting surface are formed in the reflecting prism (31, 32)being a single optical member. However, without having to be limited tothe single optical members, it is also possible, for example, to adopt aconfiguration for holding a first mirror member with the firstreflecting surface thereon and a second mirror member with the secondreflecting surface thereon so as to keep the angle invariant between thefirst reflecting surface and the second reflecting surface, and aconfiguration for holding a third mirror member with the thirdreflecting surface thereon and a fourth mirror member with the fourthreflecting surface thereon so as to keep the angle invariant between thethird reflecting surface and the fourth reflecting surface.

Namely, it is important for the sending-side reflecting section to keepthe angle invariant between the first reflecting surface and the secondreflecting surface to successively reflect the reference light, and forthe receiving-side reflecting section to keep the angle invariantbetween the third reflecting surface and the fourth reflecting surfaceto successively reflect the reference light. For this purpose, it ispreferable to integrally form the first reflecting surface and thesecond reflecting surface to successively reflect the reference light,in accordance with a required form in the sending-side reflectingsection and to integrally form the third reflecting surface and thefourth reflecting surface to successively reflect the reference light,in accordance with a required form in the receiving-side reflectingsection.

In the above configuration examples, the reference light having passedvia the sending-side common optical members (5-8) is reflected twice tobe guided to the photosensitive surface Wa, and the reference lighthaving been reflected by the photosensitive surface Wa is reflectedtwice to be guided to the receiving-side common optical members (28-25).However, without having to be limited to the twice reflectingconfiguration, it is also possible to reflect the reference light havingpassed via the sending-side common optical members (5-8), an even numberof times to guide the reference light to the photosensitive surface Waand to reflect the reference light having been reflected by thephotosensitive surface Wa, an even number of times to guide thereference light to the receiving-side common optical members (28-25). Asin this example, various forms can be contemplated as to specificconfigurations of the sending-side reflecting section and thereceiving-side reflecting section.

In the above description, the dichroic film 9 formed on the lower sideface 8 c of the rhombic prism 8 and the angle-deviating prism 10attached in proximity thereto constitute the sending-side deflectingsection which deflects the measurement light and the reference lighthaving passed via the sending-side common optical members (5-8),relative to each other to guide the measurement light to thephotosensitive surface Wa and guide the reference light to thereflecting prism 11 or 12. Furthermore, the dichroic film 29 formed onthe lower side face 28 c of the rhombic prism 28 and the angle-deviatingprism 30 attached in proximity thereto constitute the receiving-sidedeflecting section which deflects the measurement light reflected by thephotosensitive surface Wa and the reference light passing through thereflecting prism 31 or 32, relative to each other to guide them to thereceiving-side common optical members (28-25).

It is, however, noted that various forms can be contemplated as tospecific configurations of the sending-side deflecting section and thereceiving-side deflecting section. A potential configuration example is,as shown in FIG. 23, such that the sending-side deflecting section isconstituted by a dichroic film 9′ formed on the upper side face 8 b ofthe rhombic prism 8 and a triangular prism 10′ attached in proximity tothe dichroic film 9′ and that the receiving-side deflecting section isconstituted by a dichroic film 29′ formed on the upper side face 28 c ofthe rhombic prism 28 and a triangular prism 30′ attached in proximity tothe dichroic film 29′.

In this case, the measurement light Lm incident to the entrance face 8 aof the rhombic prism 8 is successively reflected by the reflecting faces8 b and 8 c, is emitted from the exit face 8 d, and is incident to thephotosensitive surface Wa. The reference light Lr incident to theentrance face 8 a of the rhombic prism 8 travels through the dichroicfilm 9′ and triangular prism 10′ to enter the reflecting prism 13. Thereference light Lr entering the reflecting prism 13 is successivelyreflected by the reflecting faces 13 a and 13 b and is then incident tothe photosensitive surface Wa.

The measurement light Lm reflected by the photosensitive surface Wa andentering the entrance face 28 c of the rhombic prism 28 is successivelyreflected by its reflecting faces 28 b and 28 c and is then emitted formthe exit face 28 d. The reference light Lr reflected by thephotosensitive surface Wa is incident into the reflecting prism 33, issuccessively reflected by its reflecting faces 33 a and 33 b, and isthen incident into the triangular prism 30′. The reference light Lrincident into the triangular prism 30′ travels through the dichroic film29′ and is emitted from the exit face 28 d of the rhombic prism 28.

In the first embodiment example, as schematically shown in FIG. 7, theintermediate images Im1-Im5 of the measurement pattern and theintermediate images Ir1-Ir5 of the reference pattern are arrayed in thesame row and the element patterns of the intermediate images Im1-Im5 ofthe measurement pattern are arrayed at the same locations on thephotosensitive surface Wa as the corresponding element patterns of theintermediate images Ir1-Ir5 of the reference pattern are. However,without having to be limited to this, for example as schematically shownin FIG. 24, it is also possible to alternately array the elementpatterns of the intermediate images Im1-Im5 of the measurement patternand the element patterns of the intermediate images Ir1-Ir5 of thereference pattern every other element pattern along one direction(X-direction) (in general, every one or more element patterns).

In this case, for example, for detecting the corrected surface positionZv3 at the detection point corresponding to the center of theintermediate image Im3 of the measurement pattern, the surface positionZm3 is calculated based on the position information of the observationimage corresponding to the intermediate image Im3. Furthermore, withfocus on the two intermediate images Ir2 and Ir3 of the referencepattern on both sides of the intermediate image Im3 in the X-direction,a surface position Zr3′ is calculated based on the position informationof the observation image corresponding to the intermediate image Ir2 andthe position information of the observation image corresponding to theintermediate image Ir3. Specifically, for example, the surface positionZr3′ is calculated as an average of the surface position Zr2 calculatedbased on the position information of the observation image correspondingto the intermediate image Ir2 and the surface position Zr3 calculatedbased on the position information of the observation image correspondingto the intermediate image Ir3.

Then the corrected surface position Zv3 at the detection pointcorresponding to the center of the intermediate image Im3 is calculatedbased on the surface position Zm3 associated with the measurement lightand the surface position Zr3′ associated with the reference light. Asfor the calculation of the corrected surface position Zvi at anotherdetection point, a surface position Zri′ can also be calculatedsimilarly based on the position information on the second observationsurface (entrance face 23Ba) corresponding to the two element patternsin the intermediate image of the reference pattern (in general, aplurality of element patterns) on both sides of the element pattern ofthe intermediate image Imi of the measurement pattern.

In the first embodiment example, each of the measurement pattern and thereference pattern is the one-dimensional array pattern in which theplurality of element patterns are arrayed along one direction. However,without having to be limited to this, it is also possible to use atwo-dimensional array pattern in which a plurality of element patternsare arrayed along two directions, as each of the measurement pattern andthe reference pattern.

In a case where each of the measurement pattern and the referencepattern used is, for example, a two-dimensional array pattern in which aplurality of element patterns are arrayed along two directionsorthogonal to each other, a plurality of element patterns ofintermediate images Im of the measurement pattern and a plurality ofelement patterns of intermediate images Ir of the reference pattern arearrayed in a matrix pattern along the X-direction and the Y-direction,as schematically shown in FIG. 25. In FIG. 25, the element patterns ofthe intermediate images Im of the measurement pattern are arrayed at thesame locations as the corresponding element patterns of the intermediateimages Ir of the reference pattern are. In this case, the detection ofthe corrected surface position Zv is as described in the firstembodiment example.

It is also possible to adopt a configuration wherein the elementpatterns of the intermediate images Im of the measurement pattern andthe element patterns of the intermediate images Ir of the referencepattern are alternately arrayed every other element pattern (in general,every one or more element patterns along two directions (X-direction andY-direction)), for example as schematically shown in FIG. 26. In thiscase, for example, for detecting a corrected surface position Zvc at adetection point corresponding to a center of an intermediate image Imcof the measurement pattern, a surface position Zmc is calculated basedon the position information of the observation image corresponding tothe intermediate image Imc.

With focus on two intermediate images Irn and Irs of the referencepattern on both sides of the intermediate image Imc along theX-direction and two intermediate images Ire and Irw of the referencepattern on both sides of the intermediate image Imc along theY-direction, a surface position Zrc is calculated based on the positioninformation of the respective observation images corresponding to theintermediate image Irn, the intermediate image Irs, the intermediateimage Ire, and the intermediate image Irw. Specifically, for example,the surface position Zrc is calculated as an average of the surfaceposition Zrn calculated based on the position information of theobservation image corresponding to the intermediate image In, thesurface position Zrs calculated based on the position information of theobservation image corresponding to the intermediate image Irs, thesurface position Zre calculated based on the position information of theobservation image corresponding to the intermediate image Ire, and thesurface position Zrw calculated based on the position information of theobservation image corresponding to the intermediate image Irw.

Alternatively, the surface position Zrc is calculated as an average ofthe surface position Zrn and the surface position Zrs, or an average ofthe surface position Zre and the surface position Zrw. Then thecorrected surface position Zvc at the detection point corresponding tothe center of the intermediate image Imc is calculated based on thesurface position Zmc associated with the measurement light and thesurface position Zrc associated with the reference light.

In general, in cases where each of the measurement pattern and thereference pattern used is an array pattern in which a plurality ofelement patterns are arrayed and where the element patterns in theintermediate image of the reference pattern are arrayed near the elementpatterns in the intermediate image of the measurement pattern, thesurface position Zm is calculated based on the position information onthe first observation surface corresponding to a selected elementpattern in the intermediate image of the measurement pattern and thesurface position Zr is calculated based on the position information onthe second observation surface corresponding to one or more elementpatterns in the intermediate image of the reference pattern arrayed nearthe selected element pattern in the intermediate image of themeasurement pattern.

In the second embodiment example and the third embodiment example, ifthe light-sending prisms 3A and 3B are integrally formed or if thelight-receiving prisms 23A and 23B are integrally formed, it becomesfeasible to avoid positional variation between the light-sending slitsSm1-Sm5 and the light-sending slits Sr1-Sr5 and unwanted positionalvariation between the observation image of the measurement pattern andthe observation image of the reference pattern and, in turn, to performhighly accurate detection.

By further integrating the light-sending prisms, it is also possible toprovide the apparatus with a light-sending member having a commonpattern surface including a measurement pattern surface provided withthe light-sending slits Sm1-Sm5 and a reference pattern surface providedwith the light-sending slits Sr1-Sr5. Likewise, by further integratingthe light-receiving prisms, it is also possible to provide the apparatuswith an observation member having a common observation surface includinga first observation surface on which the observation image of themeasurement pattern is formed and a second observation surface on whichthe observation image of the reference pattern is formed.

However, for example in the case using a common pattern surface in thesecond embodiment example, in order to make the X-directional pitch ofthe element patterns of the intermediate images Im1-Im5 of themeasurement pattern equal to the X-directional pitch of the elementpatterns of the intermediate images Ir1-Ir5 of the reference pattern onthe photosensitive surface Wa, a potential configuration is, as shown inFIG. 27, such that the pitch in an x5-direction of the element patternsof the light-sending slits Sm1-Sm5 provided on the common patternsurface 3 a of the light-sending member is made smaller than the pitchin the x5-direction of the element patterns of the light-sending slitsSr1-Sr5. For superimposing the contours of the element patterns of theintermediate images Im1-Im5 over the contours of the correspondingelement patterns of the intermediate images Ir1-Ir5 on thephotosensitive surface Wa, a potential configuration is such that thesize in the x5-direction of the element patterns of the light-sendingslits Sm1-Sm5 is made smaller than the size in the x5-direction of theelement patterns of the light-sending slits Sr1-Sr5.

The reason for it is that the incidence angle θm of the measurementlight to the photosensitive surface Wa is larger than the incidenceangle θr of the reference light. In FIG. 27, a y5-axis is set along adirection parallel to the Y-axis of the global coordinate system on thecommon pattern surface 3 a and the x5-axis is set along a directionorthogonal to the y5-axis on the common pattern surface 3 a. For makingthe X-directional pitch of the element patterns of the intermediateimages Im1-Im5 of the measurement pattern equal to the X-directionalpitch of the element patterns of the intermediate images Ir1-Ir5 of thereference pattern on the photosensitive surface Wa in the firstembodiment example and the third embodiment example as described above,a suitable configuration is such that the pitch of the element patternsof the light-sending slits Sm1-Sm5 provided on the common patternsurface 3 a of the light-sending member is also made smaller than thepitch of the element patterns of the light-sending slits Sr1-Sr5.

In each of the above-described embodiment examples, the longitudinaldirection of the slit-like element patterns of the intermediate imagesformed on the photosensitive surface Wa is set as the direction of 45°relative to the plane of incidence. However, the longitudinal directionof the slit-like element patterns is not limited only to the 45°direction to the plane of incidence, but various forms can also becontemplated as to the angle between the longitudinal direction of theslit-like element patterns and the plane of incidence. For example inthe third embodiment example, the orientation of the longitudinaldirection of the slit-like element patterns in the intermediate image ofthe reference pattern can be set in parallel with the plane of incidenceof the reference light. Namely, where the reference pattern is an arraypattern in which a plurality of slit-like element patterns are arrayed,the longitudinal direction of each slit-like element pattern in theintermediate image of the reference pattern can be made parallel to theplane of incidence of the reference light to the photosensitive surfaceWa. In this case, the moving direction of the observation image of thereference pattern corresponding to change of the surface position of thephotosensitive surface Wa (Z-directional movement) can be madecoincident with the longitudinal direction and the detection sensitivityof the surface position Zr based on the position information of theobservation image of the reference pattern can be made substantiallynull (or 0). This corresponds to the case where the incidence angle θrof the reference light to the photosensitive surface Wa is 0.

In the surface position detecting apparatus of the foregoing embodiment,the first light beam from the first pattern and the second light beamfrom the second pattern travel via the light-sending optical system toimpinge at mutually different angles on the predetermined surface. Thefirst light beam and the second light beam reflected by thepredetermined surface travel via the light-receiving optical system toform the observation image of the first pattern and the observationimage of the second pattern on the first observation surface and on thesecond observation surface, respectively. Therefore, the observationimage of the second pattern, as well as the observation image of thefirst pattern, contains information about influence of variation in anoptical member common to the first light and the second light (whichwill be called a common optical member) in the light-sending opticalsystem and in the light-receiving optical system.

In other words, a surface position of the predetermined surfacecalculated based on the position information of the observation image ofthe first pattern and a surface position of the predetermined surfacecalculated based on the position information of the observation image ofthe second pattern contain a common detection error of the surfaceposition due to variation in the common optical member. Therefore, acorrected surface position substantially free of the influence of thevariation in the common optical member can be calculated using thesurface position calculated based on the first light and the surfaceposition calculated based on the second light. Namely, the foregoingembodiment makes it feasible to highly accurately detect the surfaceposition of the predetermined surface while suppressing the influence ofthe variation in the optical member.

The surface position detecting apparatus of the foregoing embodiment hasthe sending-side reflecting section which reflects the second lighthaving passed via the sending-side common optical member, an even numberof times, for example, by first and second reflecting surfacesintegrally formed, to make the second light incident to thepredetermined surface. In this configuration, even if there is avariation in the posture of the sending-side reflecting section, theangle between the first reflecting surface and the second reflectingsurface is kept invariant and thus there is no change in the anglebetween the second light incident to the sending-side reflecting sectionand the second light emitted from the sending-side reflecting section.As a consequence, the apparatus is able to stably maintain the incidenceangle of the second light to the predetermined surface at a desiredangle and eventually to highly accurately detect the surface position ofthe predetermined surface, without being affected by variation in thesending-side reflecting section disposed in the optical path of thesecond light between the sending-side common optical member and thepredetermined surface.

In the foregoing embodiment, the surface position of the detectiontarget surface is detected based on the principle of the photoelectricmicroscope (the measurement principle with the vibrating mirror).However, without having to be limited to this, the position of thedetection target surface can also be detected, for example, by detectingthe position information of the observation image of the measurementpattern and the position information of the observation image of thereference pattern by image processing and calculating the position,based on the position information thus detected.

The aforementioned embodiment described the example in which theexposure apparatus was provided with the single surface positiondetecting apparatus, but, without having to be limited to this, thedetection field can be divided with use of a plurality of surfaceposition detecting apparatus if necessary. In this case, calibrationamong the apparatus can be implemented based on the detection results ina common field between a detection field of a first surface positiondetecting apparatus and a detection field of a second surface positiondetecting apparatus.

The aforementioned embodiment was the application of the presentinvention to the detection of the surface position of the wafer W as aphotosensitive substrate, but, without having to be limited to this, thepresent invention can also be applied to detection of a surface positionof a pattern surface of a reticle R (generally, a mask). Theaforementioned embodiment was the application of the present inventionto the detection of the surface position of the photosensitive substratein the exposure apparatus, but, without having to be limited to this,the present invention can also be applied to detection of a surfaceposition of an ordinary detection target surface in various devicesother than the exposure apparatus.

In the foregoing embodiment the surface position detecting apparatus wasconfigured to detect the surface position of the photosensitive surfaceWa, using as the detection area DA the photosensitive surface Wa nearthe optical axis AX of the projection optical system PL, but it may beconfigured to detect the surface position of the photosensitive surfaceWa at a position apart from the optical axis AX. For example, thesurface position detecting apparatus may be arranged at a positioncorresponding to a conveyance path through which the wafer W mounted onthe Z-stage VS by an unrepresented conveying device is conveyed to belowthe projection optical system PL by the XY stage HS, and configured todetect the surface position of the photosensitive surface Wa on the wayof the conveyance path. In this case, according to movement of the waferW by the XY stage HS, the surface position is measured at a plurality oflocations of the photosensitive surface Wa and the detection resultsthereof are stored in the form of map data in the storage section MR.Then the surface position of the photosensitive surface Wa may bealigned by the Z-stage VS, based on the map data stored in the storagesection MR, during the transfer (exposure) process of the pattern of thereticle R to the photosensitive surface Wa.

In the aforementioned embodiment, the mask can be replaced with avariable pattern forming device which forms a predetermined pattern onthe basis of predetermined electronic data. Use of such a variablepattern forming device can minimize influence on synchronizationaccuracy even if the pattern surface is set vertical (arrangement alonga vertical plane). The variable pattern forming device applicable hereincan be, for example, a DMD (Digital Micromirror Device) including aplurality of reflective elements driven based on predeterminedelectronic data. The exposure apparatus with the DMD is disclosed, forexample, in Japanese Patent Application Laid-open No. 2004-304135 andInternational Publication WO2006/080285. Besides the reflective spatiallight modulators of the non-emission type like the DMD, it is alsopossible to apply a transmissive spatial light modulator or aself-emission type image display device. It is noted that the variablepattern forming device can also be applied in cases where the patternsurface is set horizontal (arrangement along a horizontal plane).

The exposure apparatus of the foregoing embodiment is manufactured byassembling various sub-systems containing their respective components asset forth in the scope of claims in the present application, so as tomaintain predetermined mechanical accuracy, electrical accuracy, andoptical accuracy. For ensuring these various accuracies, the followingadjustments are carried out before and after the assembling: adjustmentfor achieving the optical accuracy for various optical systems;adjustment for achieving the mechanical accuracy for various mechanicalsystems; adjustment for achieving the electrical accuracy for variouselectrical systems. The assembling steps from the various sub-systemsinto the exposure apparatus include mechanical connections, wireconnections of electric circuits, pipe connections of pneumaticcircuits, etc. between the various sub-systems. It is needless tomention that there are assembling steps of the individual sub-systems,before the assembling steps from the various sub-systems into theexposure apparatus. After completion of the assembling steps from thevarious sub-systems into the exposure apparatus, overall adjustment iscarried out to ensure various accuracies as the entire exposureapparatus. The manufacture of exposure apparatus is desirably performedin a clean room in which the temperature, cleanliness, etc. arecontrolled.

The following will describe a device manufacturing method using theexposure apparatus according to the above-described embodiment. FIG. 28is a flowchart showing manufacturing steps of semiconductor devices. Asshown in FIG. 28, the manufacturing steps of semiconductor devicesinclude depositing a metal film on a wafer W to become a substrate ofsemiconductor devices (step S40) and applying a photoresist as aphotosensitive material onto the deposited metal film (step S42). Thesubsequent steps include transferring a pattern formed on a reticle R,into each shot area (exposure region) on the wafer W, using the exposureapparatus of the embodiment (step S44: exposure step), and developingthe wafer W after completion of the transfer, i.e., developing thephotoresist to which the pattern has been transferred (step S46:development step). Thereafter, using the resist pattern made on thesurface of the wafer W in step S46, as a mask for processing of wafer,processing such as etching is carried out on the surface of the wafer W(step S48: processing step).

The resist pattern herein is a photoresist layer (transferred patternlayer) in which depressions and projections are formed in a shapecorresponding to the pattern transferred by the exposure apparatus ofthe embodiment and which the depressions penetrate throughout. Step S48is to process the surface of the wafer W through this resist pattern.The processing carried out in step S48 includes, for example, at leasteither etching of the surface of the wafer W or deposition of a metalfilm or the like. In step S44, the exposure apparatus of the embodimentperforms the transfer of the pattern onto the wafer W coated with thephotoresist, as a photosensitive substrate.

FIG. 29 is a flowchart showing manufacturing steps of a liquid crystaldevice such as a liquid crystal display device. As shown in FIG. 29, themanufacturing steps of the liquid crystal device include sequentiallyperforming a pattern forming step (step S50), a color filter formingstep (step S52), a cell assembly step (step S54), and a module assemblystep (step S56).

The pattern forming step of step S50 is to form predetermined patternssuch as a circuit pattern and an electrode pattern on a glass substratecoated with a photoresist, as a photosensitive substrate, using theprojection exposure apparatus of the aforementioned embodiment. Thispattern forming step includes an exposure step of transferring a patternto a photoresist layer, using the exposure apparatus of the embodiment,a development step of performing development of the photosensitivesubstrate to which the pattern has been transferred, i.e., developmentof the photoresist layer on the glass substrate, to make the photoresistlayer (transferred pattern layer) in a shape corresponding to thepattern, and a processing step of processing the surface of the glasssubstrate through the developed photoresist layer.

The color filter forming step of step S52 is to form a color filter inwhich a large number of sets of three dots corresponding to R (Red), G(Green), and B (Blue) are arrayed in a matrix pattern, or in which aplurality of filter sets of three stripes of R, and B are arrayed in ahorizontal scan direction.

The cell assembly step of step S54 is to assemble a liquid crystal panel(liquid crystal cell), using the glass substrate on which thepredetermined pattern has been formed in step S50, and the color filterformed in step S52. Specifically, a liquid crystal is poured intobetween the glass substrate and the color filter to form the liquidcrystal panel. The module assembly step of step S56 is to attach variouscomponents such as electric circuits and backlights for displayoperation of this liquid crystal panel, to the liquid crystal panelassembled in step S54.

The present invention is not limited just to the application to theexposure apparatus for manufacture of semiconductor devices or liquidcrystal devices, but can also be widely applied, for example, to theexposure apparatus for display devices such as organic light emittingdisplays and plasma displays, and the exposure apparatus for manufactureof various devices such as imaging devices (CCDs and others), micromachines, thin film magnetic heads, and DNA chips. The present inventionis not applicable only to the glass substrate and semiconductor wafer,but is also applicable, for example, to a flexible sheet-like substrate(substrate in which a ratio of thickness to area is smaller than thoseof the glass substrate and semiconductor wafer) as the photosensitivesubstrate of the exposure object. Furthermore, the present invention isalso applicable to the exposure step (exposure apparatus) formanufacturing masks (photomasks, reticles, etc.) on which mask patternsof various devices are formed, by the photolithography process.

The invention is not limited to the fore going embodiments but variouschanges and modifications of its components may be made withoutdeparting from the scope of the present invention. Also, the componentsdisclosed in the embodiments may be assembled in any combination forembodying the present invention. For example, some of the components maybe omitted from all components disclosed in the embodiments. Further,components in different embodiments may be appropriately combined.

What is claimed is:
 1. A surface position detecting apparatus fordetecting a surface position of a predetermined surface, said apparatuscomprising: a light-sending optical system which makes first light froma first pattern and second light from a second pattern incident atdifferent incidence angles to the predetermined surface to project anintermediate image of the first pattern and an intermediate image of thesecond pattern onto the predetermined surface; a light-receiving opticalsystem which guides the first light and the second light reflected bythe predetermined surface, to a first observation surface and to asecond observation surface, respectively, to form an observation imageof the first pattern on the first observation surface and an observationimage of the second pattern on the second observation surface; and adetecting section which detects a piece of position information of theobservation image of the first pattern on the first observation surfaceand a piece of position information of the observation image of thesecond pattern on the second observation surface and which calculates asurface position of the predetermined surface, based on the pieces ofposition information, wherein the light-sending optical system has atleast one sending-side common optical member provided in common to thefirst light and the second light, and a sending-side reflecting sectionwhich reflects the second light having passed via the sending-sidecommon optical member, an even number of times to make the second lightincident at the incidence angle smaller than that of the first light tothe predetermined surface, wherein the sending-side reflecting sectionis arranged immediately above the predetermined surface, and wherein thelight-sending optical system has a sending-side deflecting section whichdeflects the first light and the second light having passed via thesending-side common optical member, relative to each other to guide thefirst light to the predetermined surface and the second light to thesending-side reflecting section.
 2. The surface position detectingapparatus according to claim 1, wherein the sending-side reflectingsection is arranged immediately above the intermediate image of thesecond pattern on the predetermined surface.
 3. The surface positiondetecting apparatus according to claim 1, wherein the sending-sidereflecting section makes the second light incident to the predeterminedsurface from a direction intersecting with a plane of incidence of thefirst light to the predetermined surface.
 4. The surface positiondetecting apparatus according to claim 1, wherein the sending-sidereflecting section makes the second light incident to the predeterminedsurface so that an incidence angle component of the incidence angle ofthe second light to the predetermined surface along a plane of incidenceof the first light to the predetermined surface is substantially 0°. 5.The surface position detecting apparatus according to claim 1, whereinthe light-sending optical system has a sending-side combining sectionwhich guides the first light and the second light incident from mutuallydifferent directions, to the sending-side common optical member.
 6. Thesurface position detecting apparatus according to claim 1, wherein thesecond pattern is an array pattern in which a plurality of slit-likeelement patterns are arrayed, and wherein the light-sending opticalsystem makes a longitudinal direction of the slit-like element patternsin the intermediate image of the second pattern parallel to a plane ofincidence of the second light to the predetermined surface.
 7. Thesurface position detecting apparatus according to claim 1, wherein thesending-side reflecting section has a first reflecting surface and asecond reflecting surface to successively reflect the second light, inan integrated fashion.
 8. The surface position detecting apparatusaccording to claim 1, wherein the sending-side deflecting section has asending-side separating surface which reflects one of the first lightand the second light and transmits the other.
 9. The surface positiondetecting apparatus according to claim 1, wherein the detecting sectioncalculates a first surface position Zm of the predetermined surface,based on the position information of the observation image of the firstpattern on the first observation surface, calculates a second surfaceposition Zr of the predetermined surface, based on the positioninformation of the observation image of the second pattern on the secondobservation surface, and calculates a third surface position Zv being asurface position of a detection target surface to be determined by thedetecting section, based on the following equation:Zv=(Zm−Zr)/(1−sin θr/sin θm) where θm is the incidence angle of thefirst light to the predetermined surface and θr is the incidence angleof the second light to the predetermined surface.
 10. An exposureapparatus for transferring a pattern to a photosensitive substratemounted on a substrate stage, the exposure apparatus comprising: thesurface position detecting apparatus as set forth in claim 1, whichdetects a surface position of a photosensitive surface of thephotosensitive substrate; and an aligning mechanism which achievesalignment of the substrate stage, based on a detection result of thesurface position detecting apparatus.
 11. An exposure apparatus fortransferring a pattern of a mask mounted on a mask stage, to aphotosensitive substrate mounted on a substrate stage, the exposureapparatus comprising: the surface position detecting apparatus as setforth in claim 1, which detects a surface position of at least one of aphotosensitive surface of the photosensitive substrate and a patternsurface of the mask; and an aligning mechanism which achieves relativealignment between the substrate stage and the mask stage, based on adetection result of the surface position detecting apparatus.
 12. Thesurface position detecting apparatus according to claim 1, wherein eachof the first pattern and the second pattern is an array pattern in whicha plurality of element patterns are arrayed, and wherein thelight-sending optical system makes the intermediate image of the firstpattern and the intermediate image of the second pattern arrayed inparallel on the predetermined surface.
 13. The surface positiondetecting apparatus according to claim 1, wherein the light-receivingoptical system has at least one receiving-side common optical memberprovided in common to the first light and the second light, and areceiving-side reflecting section which reflects the second lightreflected by the predetermined surface, an even number of times to guidethe second light to the receiving-side common optical member.
 14. Thesurface position detecting apparatus according to claim 7, wherein thefirst reflecting surface and the second reflecting surface are formed ina single optical member.
 15. The surface position detecting apparatusaccording to claim 8, wherein the sending-side separating surfacereflects one of the first light and the second light and transmits theother, depending upon wavelengths or polarizations of the first lightand the second light.
 16. The surface position detecting apparatusaccording to claim 9, wherein the second pattern is an array pattern inwhich a plurality of element patterns are arrayed, and wherein thedetecting section calculates the second surface position Zr, based onpieces of position information corresponding to a plurality of elementpatterns in the observation image of the second pattern.
 17. The surfaceposition detecting apparatus according to claim 9, wherein each of thefirst pattern and the second pattern is an array pattern in which aplurality of element patterns are arrayed, wherein the light-sendingoptical system makes the element patterns in the intermediate image ofthe second pattern arrayed near the element patterns in the intermediateimage of the first pattern on the predetermined surface, and wherein thedetecting section calculates the first surface position Zm, based on theposition information of the observation image of the first patterncorresponding to a selected element pattern in the intermediate image ofthe first pattern, and calculates the second surface position Zr, basedon the position information of the observation image of the secondpattern corresponding to one or more element patterns in theintermediate image of the second pattern arrayed near said selectedelement pattern in the intermediate image of the first pattern.
 18. Thesurface position detecting apparatus according to claim 17, wherein thedetecting section calculates the second surface position Zr, based onthe position information of the observation image of the second patterncorresponding to a plurality of element patterns in the intermediateimage of the second pattern on both sides of said selected elementpattern in the intermediate image of the first pattern.
 19. The exposureapparatus according to claim 10, which comprises a plane drivingmechanism to move the substrate stage in a direction along thephotosensitive surface, wherein the surface position detecting apparatusdetects surface positions at a plurality of locations on thephotosensitive surface in accordance with movement of the substratestage by the plane driving mechanism.
 20. A device manufacturing methodcomprising: transferring the pattern to the photosensitive substrate,using the exposure apparatus as set forth in claim 10; and processingthe photosensitive substrate to which the pattern has been transferred,based on the pattern.
 21. A device manufacturing method comprising:transferring the pattern to the photosensitive substrate, using theexposure apparatus as set forth in claim 11; and processing thephotosensitive substrate to which the pattern has been transferred,based on the pattern.
 22. The exposure apparatus according to claim 11,which comprises a plane driving mechanism to move the mask stage in adirection along the pattern surface, wherein the surface positiondetecting apparatus detects surface positions at a plurality oflocations on the pattern surface in accordance with movement of the maskstage by the plane driving mechanism.
 23. The exposure apparatusaccording to claim 22, comprising a storage section which stores aplurality of detection results of the surface position detectingapparatus in the form of map data.
 24. The exposure apparatus accordingto claim 19, comprising a storage section which stores a plurality ofdetection results of the surface position detecting apparatus in theform of map data.
 25. The surface position detecting apparatus accordingto claim 12, wherein the light-sending optical system makes the elementpatterns in the intermediate image of the first pattern and the elementpatterns in the intermediate image of the second pattern arrayed in arow on the predetermined surface.
 26. The surface position detectingapparatus according to claim 12, wherein the light-sending opticalsystem makes the intermediate image of the first pattern and theintermediate image of the second pattern arrayed along a plane ofincidence of the first light to the predetermined surface.
 27. Thesurface position detecting apparatus according to claim 25, wherein thelight-sending optical system makes at least one element pattern in theintermediate image of the first pattern and at least one element patternin the intermediate image of the second pattern arrayed at a location onthe predetermined surface.
 28. The surface position detecting apparatusaccording to claim 25, wherein the light-sending optical system makesthe element patterns in the intermediate image of the first pattern andthe element patterns in the intermediate image of the second patternalternately arrayed every one or more element patterns.
 29. The surfaceposition detecting apparatus according to claim 13, wherein thelight-receiving optical system has a receiving-side deflecting sectionwhich deflects the first light having been reflected by thepredetermined surface and the second light having passed via thereceiving-side reflecting section, relative to each other to guide thefirst light and the second light to the receiving-side common opticalmember.
 30. The surface position detecting apparatus according to claim13, wherein the light-receiving optical system has a receiving-sideseparating section which deflects the first light and the second lighthaving passed via the receiving-side common optical member, relative toeach other to guide the first light to the first observation surface andthe second light to the second observation surface.
 31. The surfaceposition detecting apparatus according to claim 13, wherein thelight-receiving reflecting section has a third reflecting surface and afourth reflecting surface to successively reflect the second light, inan integrated fashion.
 32. The surface position detecting apparatusaccording to claim 31, wherein the third reflecting surface and thefourth reflecting surface are formed in a single optical member.
 33. Asurface position detecting apparatus for detecting a surface position ofa predetermined surface, said apparatus comprising: a light-sendingoptical system which makes first light from a first pattern and secondlight from a second pattern incident at different incidence angles tothe predetermined surface to project an intermediate image of the firstpattern and an intermediate image of the second pattern onto thepredetermined surface; a light-receiving optical system which guides thefirst light and the second light reflected by the predetermined surface,to a first observation surface and to a second observation surface,respectively, to form an observation image of the first pattern on thefirst observation surface and an observation image of the second patternon the second observation surface; and a detecting section which detectsa piece of position information of the observation image of the firstpattern on the first observation surface and a piece of positioninformation of the observation image of the second pattern on the secondobservation surface and which calculates a surface position of thepredetermined surface, based on the pieces of position information,wherein the light-sending optical system has at least one sending-sidecommon optical member provided in common to the first light and thesecond light, and a sending-side reflecting section which reflects thesecond light having passed via the sending-side common optical member,an even number of times to make the second light incident at theincidence angle smaller than that of the first light to thepredetermined surface, wherein the light-receiving optical system has atleast one receiving-side common optical member provided in common to thefirst light and the second light, and a receiving-side reflectingsection which reflects the second light reflected by the predeterminedsurface, an even number of times to guide the second light to thereceiving-side common optical member, wherein the light-receivingoptical system has a receiving-side deflecting section which deflectsthe first light having been reflected by the predetermined surface andthe second light having passed via the receiving-side reflectingsection, relative to each other to guide the first light and the secondlight to the receiving-side common optical member, wherein thereceiving-side deflecting section has a receiving-side combining surfacewhich reflects one of the first light and the second light and transmitsthe other, and wherein the light-sending optical system has asending-side deflecting section which deflects the first light and thesecond light having passed via the sending-side common optical member,relative to each other to guide the first light to the predeterminedsurface and the second light to the sending-side reflecting section. 34.The surface position detecting apparatus according to claim 33, whereinthe receiving-side combining surface reflects one of the first light andthe second light and transmits the other, depending upon wavelengths orpolarizations of the first light and the second light.
 35. A surfaceposition detecting apparatus for detecting a surface position of apredetermined surface, said apparatus comprising: a first detectingsystem which makes first light from a first pattern incident to thepredetermined surface to project an intermediate image of the firstpattern onto the predetermined surface, which guides the first lightreflected by the predetermined surface, to a first observation surfaceto form an observation image of the first pattern on the firstobservation surface, and which detects position information of theobservation image of the first pattern on the first observation surface;a second detecting system which makes second light from a second patternincident to the predetermined surface to project an intermediate imageof the second pattern onto the predetermined surface, which guides thesecond light reflected by the predetermined surface, to a secondobservation surface to form an observation image of the second patternon the second observation surface, and which detects positioninformation of the observation image of the second pattern on the secondobservation surface; and a processing section which calculates a surfaceposition of the predetermined surface, based on the position informationof the observation image of the first pattern and the positioninformation of the observation image of the second pattern, wherein thefirst detecting system and the second detecting system have at least onesending-side common optical member provided in common to the first lightand the second light, and wherein the second detecting system has asending-side reflecting section which reflects the second light havingpassed via the sending-side common optical member, an even number oftimes to make the second light incident at an incidence angle smallerthan an incidence angle of the first light, to the predeterminedsurface, and wherein a sending-side deflecting section which deflectsthe first light and the second light having passed via the sending-sidecommon optical member, relative to each other to guide the first lightto the predetermined surface and the second light to the sending-sidereflecting section.
 36. An exposure apparatus for transferring a patternto a photosensitive substrate mounted on a substrate stage, the exposureapparatus comprising: the surface position detecting apparatus as setforth in claim 35, which detects a surface position of a photosensitivesurface of the photosensitive substrate; and an aligning mechanism whichachieves alignment of the substrate stage, based on a detection resultof the surface position detecting apparatus.
 37. An exposure apparatusfor transferring a pattern of a mask mounted on a mask stage, to aphotosensitive substrate mounted on a substrate stage, the exposureapparatus comprising: the surface position detecting apparatus as setforth in claim 35, which detects a surface position of at least one of aphotosensitive surface of the photosensitive substrate and a patternsurface of the mask; and an aligning mechanism which achieves relativealignment between the substrate stage and the mask stage, based on adetection result of the surface position detecting apparatus.
 38. Asurface position detecting method for detecting a surface position of apredetermined surface, said method comprising: making first light from afirst pattern and second light from a second pattern incident atdifferent incidence angles to the predetermined surface to project anintermediate image of the first pattern and an intermediate image of thesecond pattern onto the predetermined surface; guiding the first lightand the second light reflected by the predetermined surface, to a firstobservation surface and to a second observation surface, respectively,to form an observation image of the first pattern on the firstobservation surface and an observation image of the second pattern onthe second observation surface; and detecting a piece of positioninformation of the observation image of the first pattern on the firstobservation surface and a piece of position information of theobservation image of the second pattern on the second observationsurface, and calculating a surface position of the predeterminedsurface, based on the pieces of position information, wherein theprojecting an intermediate image of the first pattern and anintermediate image of the second pattern comprises making the firstlight and the second light travel via at least one sending-side commonoptical member provided in common to the first light and the secondlight, and reflecting the second light having passed via thesending-side common optical member, an even number of times to make thesecond light incident at the incidence angle smaller than that of thefirst light to the predetermined surface, wherein the second light isreflected the even number of times immediately above the predeterminedsurface, and wherein a light-sending optical system has a sending-sidedeflecting section which deflects the first light and the second lighthaving passed via the sending-side common optical member, relative toeach other to guide the first light to the predetermined surface and thesecond light to a sending-side reflecting section.
 39. A surfaceposition detecting method for detecting a surface position of apredetermined surface, said method comprising: making first light from afirst pattern incident to the predetermined surface to project anintermediate image of the first pattern onto the predetermined surface,guiding the first light reflected by the predetermined surface, to afirst observation surface to form an observation image of the firstpattern on the first observation surface, and detecting positioninformation of the observation image of the first pattern on the firstobservation surface; making second light from a second pattern incidentto the predetermined surface to project an intermediate image of thesecond pattern onto the predetermined surface, guiding the second lightreflected by the predetermined surface, to a second observation surfaceto form an observation image of the second pattern on the secondobservation surface, and detecting position information of theobservation image of the second pattern on the second observationsurface; and calculating a surface position of the predeterminedsurface, based on the position information of the observation image ofthe first pattern and the position information of the observation imageof the second pattern, wherein the detecting position information of theobservation image of the first pattern and the detecting positioninformation of the observation image of the second pattern comprisemaking the first light and the second light, respectively, travel via atleast one sending-side common optical member provided in common to thefirst light and the second light, wherein the detecting positioninformation of the observation image of the second pattern comprisesreflecting the second light having passed via the sending-side commonoptical member, an even number of times to make the second lightincident at an incidence angle smaller than an incidence angle of thefirst light, to the predetermined surface, and wherein the first lightand the second light having passed via the sending-side common opticalmember are deflected relative to each other, and then the first light isguided to the predetermined surface and the second light relativelydeflected is incident on the predetermined surface after being reflectedthe even number of times.